Humans do not avoid reactively implementing cognitive control

The ability to exert cognitive control allows us to achieve goals in the face of distraction and competing actions. However, control is costly-people generally aim to minimize its demands. Because control takes many forms, it is important to understand whether such costs apply universally. Specifically, reactive control, which is recruited in response to stimulus or contextual features, is theorized to be deployed automatically, and not depend on attentional resources. Here, we investigated whether people avoided implementing reactive control in three experiments. In all, participants performed a Stroop task in which certain items were mostly incongruent (MI), that is, associated with a high likelihood of conflict (triggering a focused control setting). Other items were mostly congruent, that is, associated with a low likelihood of conflict (triggering a relaxed control setting). Experiment 1 demonstrated that these control settings transfer to a subsequent unbiased transfer phase. In Experiments 2-3, we used a demand selection task to investigate whether people would avoid choice options that yielded items that were previously MI. In all, participants continued to retrieve focused control settings for previously MI items, but they did not avoid them in the demand selection task. Critically, we only found demand avoidance when there was an objective difference in demand between options. These findings are consistent with the idea that implementing reactive control does not register as costly. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Between-task transfer of item-specific control is replicable and extends to novel conditions

Learning-guided control refers to adjustments of cognitive control settings based on learned associations between predictive cues and the likelihood of conflict. In three preregistered experiments, we examined transfer of item-specific control settings beyond conditions under which they were learned. In Experiment 1, an item-specific proportion congruence (ISPC) manipulation was applied in a training phase in which target color in a Flanker task was biased (mostly congruent or mostly incongruent). In a subsequent transfer phase, participants performed a color-word Stroop task in which the same target colors were unbiased (50% congruent). The same design was implemented in Experiment 2, but training and transfer tasks were intermixed within blocks. Between-task transfer was evidenced in both experiments, suggesting learned control settings associated with the predictive cues were retrieved when encountering unbiased transfer items. In Experiment 3, we investigated a farther version of between-task transfer by using training (color-word Stroop) and transfer (picture-word Stroop) tasks that did not share the relevant (to-be-named) dimension or response sets. Despite the stronger, between-task boundary, we observed an ISPC effect for the transfer items, but it did not emerge until the second half of the experiment. The results provided converging evidence for the flexibility and automaticity of item-specific control. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

On the psychometric evaluation of cognitive control tasks: An Investigation with the Dual Mechanisms of Cognitive Control (DMCC) battery

The domain of cognitive control has been a major focus of experimental, neuroscience, and individual differences research. Currently, however, no theory of cognitive control successfully unifies both experimental and individual differences findings. Some perspectives deny that there even exists a unified psychometric cognitive control construct to be measured at all. These shortcomings of the current literature may reflect the fact that current cognitive control paradigms are optimized for the detection of within-subject experimental effects rather than individual differences. In the current study, we examine the psychometric properties of the Dual Mechanisms of Cognitive Control (DMCC) task battery, which was designed in accordance with a theoretical framework that postulates common sources of within-subject and individual differences variation. We evaluated both internal consistency and test-retest reliability, and for the latter, utilized both classical test theory measures (i.e., split-half methods, intraclass correlation) and newer hierarchical Bayesian estimation of generative models. Although traditional psychometric measures suggested poor reliability, the hierarchical Bayesian models indicated a different pattern, with good to excellent test-retest reliability in almost all tasks and conditions examined. Moreover, within-task, between-condition correlations were generally increased when using the Bayesian model-derived estimates, and these higher correlations appeared to be directly linked to the higher reliability of the measures. In contrast, between-task correlations remained low regardless of theoretical manipulations or estimation approach. Together, these findings highlight the advantages of Bayesian estimation methods, while also pointing to the important role of reliability in the search for a unified theory of cognitive control.

Sequence effects and speech processing: cognitive load for speaker-switching within and across accents

Prior work in speech processing indicates that listening tasks with multiple speakers (as opposed to a single speaker) result in slower and less accurate processing. Notably, the trial-to-trial cognitive demands of switching between speakers or switching between accents have yet to be examined. We used pupillometry, a physiological index of cognitive load, to examine the demands of processing first (L1) and second (L2) language-accented speech when listening to sentences produced by the same speaker consecutively (no switch), a novel speaker of the same accent (within-accent switch), and a novel speaker with a different accent (across-accent switch). Inspired by research on sequential adjustments in cognitive control, we aimed to identify the cognitive demands of accommodating a novel speaker and accent by examining the trial-to-trial changes in pupil dilation during speech processing. Our results indicate that switching between speakers was more cognitively demanding than listening to the same speaker consecutively. Additionally, switching to a novel speaker with a different accent was more cognitively demanding than switching between speakers of the same accent. However, there was an asymmetry for across-accent switches, such that switching from an L1 to an L2 accent was more demanding than vice versa. Findings from the present study align with work examining multi-talker processing costs, and provide novel evidence that listeners dynamically adjust cognitive processing to accommodate speaker and accent variability. We discuss these novel findings in the context of an active control model and auditory streaming framework of speech processing.

Age-Related Differences in Mind Wandering: The Role of Emotional Valence

OBJECTIVES

Older adults consistently report fewer experiences of mind wandering compared to younger adults. Aging is also associated with a shift in the emotional focus of our thoughts, with older adults tending to experience an increase in attention toward positive information, or a "positivity bias," relative to younger adults. Here, we tested if the positivity bias associated with aging can also predict age-related changes in the content of older adults' mind wandering.

METHOD

Older adults and younger adults completed a go/no-go task with periodic thought probes to assess rates of emotionally valenced mind wandering.

RESULTS

Older adults reported significantly less negatively and neutrally valenced mind wandering compared to younger adults, but there was no age difference in reports of positively valenced mind wandering. Overall rates of mind wandering predicted poorer task performance for both age groups: Individuals who mind wandered more, performed worse, but this did not differ by the emotional valence. Both older adults and younger adults showed similar in-the-moment performance deficits, with mind wandering reports being associated with worse immediate no-go accuracy and faster reaction times, consistent with mindless responding.

DISCUSSION

Focusing on different dimensions of thought content, such as emotional valence, can provide new insight into age-related differences in mind wandering. Older adults' mind wandering reports were less negative and neutral compared to younger adults' reports suggesting a positivity bias for older adults. However, this positivity bias does not seem to affect task performance. We discuss the implications of the findings for mind wandering theories and the positivity bias.

Revealing object-based cognitive control in a moving object paradigm

Object-based attention and flexible adjustments of cognitive control based on contextual cues signaling the likelihood of distraction are well documented. However, no prior research has conclusively demonstrated that people flexibly adjust cognitive control to minimize distraction based on learned associations between task-irrelevant objects and distraction likelihood (i.e., object-based cognitive control). To fill this gap, we developed a novel paradigm during which participants responded to flanker stimuli appearing in one of multiple locations on two simultaneously presented objects. One object predicted a low likelihood of encountering an incongruent flanker stimulus and the other a high likelihood. After each response, the objects rotated clockwise such that all locations on average were 50% congruent, thereby eliminating confounds between location and likelihood of incongruence. Object-based cognitive control was evidenced by reduced flanker compatibility effects in the high compared to low conflict object. Across four experiments, we demonstrated that object-based cognitive control was dependent on a strong manipulation of the likelihood of conflict between objects and movement of the objects between trials. The novel evidence for object-based cognitive control is important in showing that people exploit not only location as a cue to guide control, but additionally objects, mirroring evidence on object and location-based attention. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

The location-specific proportion congruence effect: Are left/right locations special?

People reactively adjust attentional control based on the history of conflict experiences at different locations resulting in location-specific proportion compatibility (LSPC) effects. Weidler et al. (2022, Journal of Experimental Psychology: Human Perception and Performance, 48[4], 312-330) found that LSPC effects were larger when stimuli were presented on the horizontal axis (i.e., locations to left and right of fixation) compared with the vertical axis (i.e., locations above and below fixation). They proposed and provided initial evidence suggesting left/right locations may represent a special design feature that leads to stronger LSPC effects (i.e., horizontal precedence account). However, their use of horizontally oriented flanker stimuli, which required participants to traverse through the distracting flankers to select the central target selectively in the horizontal axis condition, may have contributed to the horizontal advantage they observed (i.e., gaze path account). The present study tested competing predictions of these two accounts. Experiment 1 used vertically oriented flanker stimuli and compared the findings with Weidler et al. The LSPC effect was larger for vertically oriented stimuli on the vertical axis, and horizontally oriented stimuli on the horizontal axis, supporting the gaze path account. Experiment 2 used flanker stimuli that required participants to traverse through distracting flankers regardless of the axis on which stimuli were presented. The LSPC effect was equivalent between the vertical axis and horizontal axis conditions. These results further supported the gaze path account and suggest that the critical design feature for amplifying LSPC effects is not left/right locations per se, but rather use of stimuli/axis combinations that encourage processing of the distractor dimension.

Dissociating proactive and reactive control in older adults

The Dual Mechanisms of Control framework predicts that age-related declines should be most prominent for tasks that require proactive control, while tasks requiring reactive control should show minimal age differences in performance. However, results from traditional paradigms are inconclusive as to whether these two processes are independent, making it difficult to understand how these processes change with age. The present study manipulated the proportion congruency in a list-wide (Experiments 1 and 2) or item-specific (Experiment 1) fashion to independently assess proactive and reactive control, respectively. In the list-wide task, older adults were unable to proactively bias attention away from word processing based on list-level expectancies. Proactive control deficits replicated across multiple task paradigms, with different Stroop stimuli (picture-word, integrated color-word, separated color-word), and different behavioral indices (Stroop interference, secondary prospective memory). In contrast, older adults were successfully able to reactively filter the word dimension based on item-specific expectancies. These findings provide unambiguous support that aging is associated with declines in proactive, but not reactive, control. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Transfer of learned cognitive control settings within and between tasks

Cognitive control is modulated based on learned associations between conflict probability and stimulus features such as color. We investigated whether such learning-guided control transfers to novel stimuli and/or a novel task. In Experiments 1 and 2, participants experienced an item-specific proportion congruence (ISPC) manipulation in a Stroop (Experiment 1) or Flanker (Experiment 2) task with mostly congruent (MC) and mostly incongruent (MI) colors in training blocks. During a transfer block, participants performed the same task and encountered novel transfer stimuli paired with MC or MI colors. Evidencing within-task transfer, in both experiments, responses were faster to incongruent transfer stimuli comprising an MI color compared with an MC color. In Experiment 3, we investigated between-task transfer from Stroop to Flanker. After training with an ISPC manipulation in the Stroop task, a Flanker task was completed with the same colors but without an ISPC manipulation (i.e., 50% congruent). Responses were faster to incongruent transfer stimuli paired with the previously-MI colors compared with the previously-MC colors. Additionally, transfer was evident in the first half of the Flanker task but not the second half. The evidence for within-task transfer, in combination with the novel evidence for between-task transfer, suggests learned control settings are flexibly retrieved and executed when predictive cues signaling these control settings are encountered in novel stimuli or a novel task. Theoretical implications are discussed alongside potential neural mechanisms mediating transfer of learning-guided control.

The Dual Mechanisms of Cognitive Control (DMCC) project: Validation of an online behavioural task battery

Cognitive control serves a crucial role in human higher mental functions. The Dual Mechanisms of Control theoretical framework provides a unifying account that decomposes cognitive control into two qualitatively distinct mechanisms-proactive control and reactive control. Here, we describe the Dual Mechanisms of Cognitive Control (DMCC) task battery, which was developed to probe cognitive control modes in a theoretically targeted manner, along with detailed descriptions of the experimental manipulations used to encourage shifts to proactive or reactive mode in each of four prototypical domains of cognition: selective attention, context processing, multitasking, and working memory. We present results from this task battery, conducted from a large (N > 100), online sample that rigorously evaluates the group effects of these manipulations in primary indices of proactive and reactive control, establishing the validity of the battery in providing dissociable yet convergent measures of the two cognitive control modes. The DMCC battery may be a useful tool for the research community to examine cognitive control in a theoretically targeted manner across different individuals and groups.

The dominance of item learning in the location-specific proportion congruence paradigm

Prior research has shown that various cues are exploited to reactively adjust attention, and such adjustments depend on learning associations between cues and proportion congruence. This raises the intriguing question of what will be learned when more than one cue is available, a question that has implications for understanding which cue(s) will dominate in guiding reactive adjustments. Evidence from a picture-word Stroop task demonstrated that item learning dominated over location learning in a location-specific proportion congruence (LSPC) paradigm, a pattern that may explain the difficulty researchers have faced in replicating and reproducing the LSPC effect. One goal was to reproduce this pattern using a non-overlapping two-item set design that more closely matched prior studies, and another goal was to examine generalisability of the pattern to two other tasks. Using a prime-probe, colour-word Stroop task (Experiment 1), and a flanker task (Experiment 2), we again found clear dominance of item learning. In Experiment 3, we attempted to disrupt item learning and promote location learning by using a counting procedure that directed participants' attention to location. Once again, we found the same pattern of item dominance. In addition, in none of the experiments did we find evidence for conjunctive (location-item) learning. Collectively, the findings suggest item learning is neither design- or task-specific; rather, it is robust, reliable, and not easily disrupted. Discussion centres on factors dictating dominance of item- over location-based adjustments and implications for the broader literature on LSPC effects.

A multimodal analysis of sustained attention in younger and older adults

Age-related cognitive decline has been attributed to processing speed differences, as well as differences in executive control and response inhibition. However, recent research has shown that healthy older adults have intact, if not superior, sustained attention abilities compared to younger adults. The present study used a combination of reaction time (RT), thought probes, and pupillometry to measure sustained attention in samples of younger and older adults. The RT data revealed that, while slightly slower overall, older adults sustained their attention to the task better than younger adults, and did not show a vigilance decrement. Older adults also reported fewer instances of task-unrelated thoughts and reported feeling more motivated and alert than younger adults, despite finding the task more demanding. Additionally, older adults showed larger, albeit later-peaking, task-evoked pupillary responses (TEPRs), corroborating the behavioral and self-report data. Finally, older adults did not show a shallowing of TEPRs across time, corroborating the finding that their RTs also did not change across time. The present findings are interpreted in light of processing speed theory, resource-depletion theories of vigilance, and recent neurological theories of cognitive aging. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

How is location defined? Implications for learning and transfer of location-specific control

Much research has explored location-specific proportion compatibility (LSPC) effects (i.e., how the appearance of a stimulus in certain locations can reactively trigger different attentional control settings) to elucidate mechanisms underlying reactive control. Recently, however, failures to reproduce key evidence showing transfer of LSPC effects (originally reported in Crump & Milliken, 2009) have called into question whether control per se supports these effects. Notably, Crump and Milliken (2009), and all studies attempting to reproduce their findings, presented stimuli in two locations, one above and one below fixation. Inspired by research on differences between horizontal and vertical meridians, we examined the consequences of defining location in this way compared with alternatives. Experiments 1 and 2 demonstrated that LSPC effects are robust when location is defined as left versus right and larger than when location is defined as upper versus lower, and additionally demonstrated LSPC effects for two locations within the same coarse spatial category (e.g., left vs. farther left). In Experiment 3, we aimed to reproduce Crump and Milliken's key findings using left and right locations for the first time. Critically, we found transfer of the LSPC effect to diagnostic items across two designs and the first evidence for a robust experiment wide LSPC effect for inducer items. Our findings support theories positing that LSPC effects reflect location-specific attentional control and more generally suggest that choosing a definition of location is not a minor methodological decision but critically impacts learning and transfer of location-specific attentional control. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

The shaping of cognitive control based on the adaptive weighting of expectations and experience

Existing approaches in the literature on cognitive control in conflict tasks almost exclusively target the outcome of control (by comparing mean congruency effects) and not the processes that shape control. These approaches are limited in addressing a current theoretical issue-what contribution does learning make to adjustments in cognitive control? In the present study, we evaluated an alternative approach by reanalyzing existing data sets using generalized linear mixed models that enabled us to examine trial-level changes in control within abbreviated lists that varied in theoretically significant ways (e.g., probability of conflict; presence vs. absence of a precue). For the first time, this allowed us to characterize (a) the trial-by-trial signature of experience-based processes that support control as a list unfolds under various conditions and (b) how explicit precues conveying the expected probability of conflict within a list influence control learning. This approach uncovered novel theoretical insights: First, slopes representing control learning varied depending on whether a cue was available or not suggesting that explicit expectations about conflict affected whether and the rate at which control learning occurred; and second, this pattern was modulated by task demands and incentives. Additionally, analyses revealed a cue-induced heightening of control in high conflict likelihood lists that mean level analyses had failed to capture. The present study showed how control is shaped by the adaptive weighting of experience and expectations on a trial-by-trial basis and demonstrated the utility of a novel method for revealing the contributions of learning to control, and modulation of learning via precues. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

A Representational Similarity Analysis of Cognitive Control during Color-Word Stroop

Progress in understanding the neural bases of cognitive control has been supported by the paradigmatic color-word Stroop task, in which a target response (color name) must be selected over a more automatic, yet potentially incongruent, distractor response (word). For this paradigm, models have postulated complementary coding schemes: dorsomedial frontal cortex (DMFC) is proposed to evaluate the demand for control via incongruency-related coding, whereas dorsolateral PFC (DLPFC) is proposed to implement control via goal and target-related coding. Yet, mapping these theorized schemes to measured neural activity within this task has been challenging. Here, we tested for these coding schemes relatively directly, by decomposing an event-related color-word Stroop task via representational similarity analysis. Three neural coding models were fit to the similarity structure of multivoxel patterns of human fMRI activity, acquired from 65 healthy, young-adult males and females. Incongruency coding was predominant in DMFC, whereas both target and incongruency coding were present with indistinguishable strength in DLPFC. In contrast, distractor information was strongly encoded within early visual cortex. Further, these coding schemes were differentially related to behavior: individuals with stronger DLPFC (and lateral posterior parietal cortex) target coding, but weaker DMFC incongruency coding, exhibited less behavioral Stroop interference. These results highlight the utility of the representational similarity analysis framework for investigating neural mechanisms of cognitive control and point to several promising directions to extend the Stroop paradigm.SIGNIFICANCE STATEMENT How the human brain enables cognitive control - the ability to override behavioral habits to pursue internal goals - has been a major focus of neuroscience research. This ability has been frequently investigated by using the Stroop color-word naming task. With the Stroop as a test-bed, many theories have proposed specific neuroanatomical dissociations, in which medial and lateral frontal brain regions underlie cognitive control by encoding distinct types of information. Yet providing a direct confirmation of these claims has been challenging. Here, we demonstrate that representational similarity analysis, which estimates and models the similarity structure of brain activity patterns, can successfully establish the hypothesized functional dissociations within the Stroop task. Representational similarity analysis may provide a useful approach for investigating cognitive control mechanisms.

On the automaticity of reactive item-specific control as evidenced by its efficiency under load

Traditionally cognitive control is described as slow-acting, effortful, and strategic. Against this backdrop, the notion of "automatic control" is an oxymoron. However, recent findings indicate control also operates quickly with adjustments occurring outside awareness, leaving open the possibility that control could be automatic under certain conditions. Harnessing one such finding, the item-specific proportion congruent (ISPC) effect (i.e., reduction in congruency effect for mostly incongruent compared with mostly congruent items), we systematically investigated the automaticity of reactive item-specific control by examining its efficiency under a concurrent load. In four experiments using a picture-word Stroop task, participants first performed a block of trials in which an ISPC manipulation was embedded to acquire the item-control associations. In later blocks, we manipulated working memory load within-subjects (verbal in Experiment 1, visuospatial in Experiment 2, and n-back updating in Experiments 3 and 4) and compared the ISPC effect between low- and high-load conditions. The results of all four experiments showed that the ISPC effect was robust regardless of working memory load. In Experiment 4, we additionally included diagnostic items to assess whether transfer of item-specific control settings was also automatic. The ISPC transfer effect was abolished under high working memory load. Collectively, the findings suggest that reactive item-specific control is triggered and executed in an automatic manner (regardless of the available attentional resources), but only for items that directly support learning of the item-control associations that underlie item-specific control. We propose several hypotheses to account for these findings and discuss theoretical implications for control. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Conflict-induced perceptual filtering: A mechanism supporting location-specific control?

Cognitive control can adapt to the level of conflict present in the environment in a proactive (pre-stimulus onset) or reactive (post-stimulus onset) manner. This is evidenced by list-wide and location-specific proportion congruence effects, reduced interference in higher conflict lists or locations, respectively. Proactive control in the flanker task is believed to be supported by a conflict-induced-filtering (CIF) mechanism. The goal of the present set of experiments was to test if CIF also supports reactive location-specific control in the flanker task. To measure CIF, we interspersed a visual search task with a flanker task. After reproducing evidence for CIF using a two-location, list-wide proportion congruence manipulation (Experiment 1), we examined if a similar pattern emerges using a location-specific proportion congruence manipulation in Experiments 2 - 5. We found minimal evidence that reactive location-specific control employs a CIF mechanism. What was clear, however, is that the location-specific proportion congruence effect is susceptible to disruption from an intermixed task that dilutes the location-conflict signal. This highlights the need for alternative approaches to elucidate whether CIF or another mechanism supports reactive, location-specific control.

List-level control in the flanker task

Current theories posit multiple levels of cognitive control for resolving conflict, including list-level control: the global or proactive biasing of attention across a list of trials. However, to date, evidence for pure list-level control has largely been confined to the Stroop task. Our goals were twofold: (a) test the generality of theoretical accounts by seeking evidence for list-level control in the letter flanker task, using an established method involving diagnostic items, and investigating the conditions under which list-level control may and may not be observed and (b) develop and test a potential solution to the challenge of isolating list-level control in tasks with a relatively limited set of stimuli and responses such as arrow flanker. Our key findings were that list-level control was observed for the first time in a letter flanker task on diagnostic items (Experiment 1), and it was not observed when the design was altered to encourage learning and use of simple stimulus–response associations (Experiment 2). These findings support the generalisability of current theoretical accounts positing dual-mechanisms or multiple levels of control, and the associations as antagonists to control account positing that list-level control may be a last resort, to conflict tasks besides Stroop. List-level control was also observed in the arrow flanker task using a modified design (Experiment 3), which could be extended to other conflict tasks with limited sets of stimuli (four or fewer), although this solution is not entirely free of confounds.

The unique effects of relatively recent conflict on cognitive control

In tasks like Stroop, it is well documented that cognitive control is affected by experiences with past conflict on 2 timescales. The "immediate" timescale is evidenced by congruency sequence effects while the "long" timescale is evidenced by list-wide proportion congruence effects. What remains underspecified is whether relatively recent experiences with conflict (i.e. recent timescale of a few preceding trials) also uniquely affect control and how experiences on different timescales are weighted. We conducted 3 preregistered experiments using a novel Stroop paradigm designed to isolate the effects of the recent timescale and measured cognitive control via diagnostic items. In Experiment 1, we manipulated the level of conflict experienced in the recent timescale within mostly congruent and mostly incongruent lists. Controlling for conflict experiences in the long and immediate timescales, we found that conflict in the recent timescale affected cognitive control and did so similarly across list types. In Experiment 2 we found a boundary condition for the effects of recent conflict -when the recent timescale was preceded by 50% congruent trials, conflict in the recent timescale did not affect cognitive control. Experiment 3 systematically replicated the findings of Experiment 1 and demonstrated that conflict in the recent timescale affected cognitive control even after a long unfilled delay between recent conflict and subsequent diagnostic trials. These novel findings expand understanding of how conflict experiences in the recent timescale affect cognitive control and highlight the need to expand theories of cognitive control to incorporate the recent timescale and its interaction with other timescales. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

What can be learned in a context-specific proportion congruence paradigm? Implications for reproducibility

Crump and Milliken (2009) reported a context-specific proportion congruence (CSPC) effect for inducer and diagnostic sets, the strongest evidence to date of context-specific control. Attempts to replicate/reproduce this evidence have failed, including Experiment 1. Using a picture-word Stroop task, we tackled the question of how to interpret such failures by testing the consistency hypothesis (Hutcheon & Spieler, 2017) and two novel hypotheses inspired by our theorizing about learning opportunities in the CSPC paradigm. Experiment 2 found a CSPC effect when there was no diagnostic set, supporting the consistency hypothesis. Experiment 3 produced novel evidence for item-PC learning in a CSPC paradigm. In contrast, Experiment 4 did not produce strong evidence for location-item conjunctive learning. Our findings suggest failures to replicate/reproduce the CSPC effect do not necessarily indicate a Type I error or instability but instead may indicate episodic representations were organized based on item and not location. This item-PC learning hypothesis uniquely predicted Experiment 3 findings and accommodates findings of all but one prior attempt to replicate/reproduce the CSPC effect for inducer and diagnostic sets, including Experiment 1. Predicting whether future attempts are successful will require deeper understanding of the factors that promote learning of item-PC versus location-PC associations. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Aftereffects and deactivation of completed prospective memory intentions: A systematic review

Prospective memory, the ability to perform an intended action in the future, is an essential aspect of goal-directed behavior. Intentions influence our behavior and shape the way we process and interact with our environment. One important question for research on prospective memory and goal-directed behavior is whether this influence stops after the intention has been completed successfully. Are intention representations deactivated from memory after their completion, and if so, how? Here, we systematically review 20 years of research on intention deactivation and so-called aftereffects of completed intentions across different research fields to offer an integrative perspective on this topic. We first introduce the currently dominant accounts of aftereffects (inhibition vs. retrieval) and illustrate the paradigms, findings, and interpretations that these accounts developed from. We then review the evidence for each account based on the extant research in these paradigms. While early studies proposed a rapid deactivation or even inhibition of completed intentions, more recent studies mostly suggested that intentions continue to be retrieved even after completion and interfere with subsequent performance. Although these accounts of aftereffects seem mutually exclusive, we will show that they might be two sides of the same coin. That is, intention deactivation and the occurrence of aftereffects are modulated by a multitude of factors that either foster a rapid deactivation or lead to continued retrieval of completed intentions. Lastly, we outline future directions and novel experimental procedures for research on mechanisms and modulators of intention deactivation and discuss practical implications of our findings. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

Measuring Adaptive Control in Conflict Tasks

The past two decades have witnessed an explosion of interest in the cognitive and neural mechanisms of adaptive control processes that operate in selective attention tasks. This has spawned not only a large empirical literature and several theories but also the recurring identification of potential confounds and corresponding adjustments in task design to create confound-minimized metrics of adaptive control. The resulting complexity of this literature can be difficult to navigate for new researchers entering the field, leading to suboptimal study designs. To remediate this problem, we present here a consensus view among opposing theorists that specifies how researchers can measure four hallmark indices of adaptive control (the congruency sequence effect, and list-wide, context-specific, and item-specific proportion congruency effects) while minimizing easy-to-overlook confounds.

The effects of awareness and secondary task demands on Stroop performance in the pre-cued lists paradigm

Prior research has demonstrated that explicit pre-cues informing participants of the proportion congruence of an upcoming list of Stroop trials affect performance in mostly congruent lists but not mostly incongruent lists. This pattern suggests a limited role for expectations in influencing Stroop performance. An alternative explanation, however, is that the effects of pre-cues may be masked by a bleed-over of awareness (of the proportion congruence manipulation) from cued to uncued lists given use of a within-subjects manipulation of cueing in prior research. One aim of the current study was to test this explanation by examining patterns of cueing effects when cueing is manipulated between subjects. A second aim was to examine the effects of a secondary, stimulus detection task on expectation and experience-driven effects in the pre-cued lists paradigm. Countering the bleed-over of awareness account, the prior finding of a selective effect of expectations in mostly congruent lists was again observed in the current experiments, and post-experimental assessments of awareness in the uncued condition were unrelated to Stroop performance. Additionally, it was demonstrated that the secondary task did not disrupt experience-driven control but did disrupt the expectation-driven use of pre-cues especially when participants did not know that secondary task stimuli would appear in advance of a list. These findings advance our understanding of the role of awareness in patterns of Stroop performance, and raise interesting questions about the types of advance knowledge that can be integrated in an expectation-driven fashion to optimize Stroop performance.

The flexibility of cognitive control: Age equivalence with experience guiding the way

Prior research has shown that aging is accompanied by changes in cognitive control. Older adults are less effective in maintaining an attentional bias in favor of goal-relevant information and are less flexible in shifting control relative to younger adults. Using a novel variant of the Stroop color-naming task, we tested the hypothesis that age-related differences in the flexible shifting of control may be small or absent when control is guided by experience (i.e., environmental input guiding attention). Younger and older adults named the color of color words in abbreviated lists of trials. In Experiment 1, experience within the early segment of the list was manipulated to encourage adoption of more (mostly congruent condition) or less (mostly incongruent condition) attention toward the word. More important, the middle and late portions were 50% congruent in both conditions. Older adults, like younger adults, demonstrated flexible acquisition and shifting of control settings (i.e., relative attention to word vs. color information). In Experiment 2 we replicated this finding. Additionally, we found that both age groups flexibly acquired and shifted control settings for "transfer" items (i.e., items that were 50% congruent in all lists and list segments), pointing to a generalizable (i.e., global) form of control rather than an item-specific mechanism. Discussion focuses on the role of experience-guided control in enabling flexible performance in older adults. (PsycINFO Database Record

Context cue focality influences strategic prospective memory monitoring

Monitoring the environment for the occurrence of prospective memory (PM) targets is a resource-demanding process that produces cost (e.g., slower responding) to ongoing activities. However, research suggests that individuals are able to monitor strategically by using contextual cues to reduce monitoring in contexts in which PM targets are not expected to occur. In the current study, we investigated the processes supporting context identification (i.e., determining whether or not the context is appropriate for monitoring) by testing the context cue focality hypothesis. This hypothesis predicts that the ability to monitor strategically depends on whether the ongoing task orients attention to the contextual cues that are available to guide monitoring. In Experiment 1, participants performed an ongoing lexical decision task and were told that PM targets (TOR syllable) would only occur in word trials (focal context cue condition) or in items starting with consonants (nonfocal context cue condition). In Experiment 2, participants performed an ongoing first letter judgment (consonant/vowel) task and were told that PM targets would only occur in items starting with consonants (focal context cue condition) or in word trials (nonfocal context cue condition). Consistent with the context cue focality hypothesis, strategic monitoring was only observed during focal context cue conditions in which the type of ongoing task processing automatically oriented attention to the relevant features of the contextual cue. These findings suggest that strategic monitoring is dependent on limited-capacity processing resources and may be relatively limited when the attentional demands of context identification are sufficiently high.

Aging and the strategic use of context to control prospective memory monitoring

Monitoring the environment for the occurrence of prospective memory (PM) targets is a resource-demanding process that produces cost to ongoing activities. The current study investigated younger and older adults' ability to monitor strategically, which involves the heightening and relaxation of monitoring when it is contextually appropriate thereby affording conservation of limited-capacity attentional resources. Participants performed a lexical-decision task in which words or nonwords were presented in upper or lower locations of the screen. The specific condition was correctly informed that PM targets ("tor" syllable) would occur only in word trials (simple cue; Experiment 1), in word trials in the upper location (complex cue; Experiments 2 and 3A), or in red trials in the upper location (complex cue; Experiment 3B), whereas the nonspecific condition was told that targets could appear in any context. The results showed that older adults generally exhibited similar monitoring patterns as younger adults. When context varied randomly on each trial, younger and older adults in the specific condition utilized simple (Experiment 1) but not complex (Experiment 2) contextual cues to reduce monitoring in unexpected contexts relative to the nonspecific condition. Notably, younger but not older adults were able to use the location dimension of the complex cue to reduce monitoring in unexpected (lower) contexts. When context varied more predictably (i.e., changed every eight trials), both younger and older adults were able to monitor strategically in response to the complex contextual cue (Experiments 3A and 3B). Together these findings suggest that context-sensitive PM monitoring processes generally remain intact with increased age. (PsycINFO Database Record

Attentional control transfers beyond the reference frame

Much research has shown that humans can allocate attentional control differentially to multiple locations based on the amount of conflict historically associated with a given location. Additionally, once established, these control settings can transfer to nearby locations that themselves have no conflict bias. Here we examined if these control settings also extend to nearby locations that are presented outside of the original frame of reference of biased stimuli. During training, participants first responded to biased flanker stimuli that were likely high conflict in one location and low conflict in another location. Then they were exposed to two sets of unbiased stimuli presented in novel transfer locations outside of the established reference frame of biased stimuli. Across three experiments, attentional control settings transferred beyond the reference frame including when there was a visual border (Experiment 2) or meaningful categorical distinction (Experiment 3) delineating training and transfer locations. These novel findings further support the idea that stimulus-driven attention control can be flexibly allocated, perhaps in a categorical manner.

Cognitive effort is modulated outside of the explicit awareness of conflict frequency: Evidence from pupillometry

Classic theories of cognitive control conceptualized controlled processes as slow, strategic, and willful, with automatic processes being fast and effortless. The context-specific proportion compatibility (CSPC) effect, the reduction in the compatibility effect in a context (e.g., location) associated with a high relative to low likelihood of conflict, challenged classic theories by demonstrating fast and flexible control that appears to operate outside of conscious awareness. Two theoretical questions yet to be addressed are whether the CSPC effect is accompanied by context-dependent variation in effort, and whether the exertion of effort depends on explicit awareness of context-specific task demands. To address these questions, pupil diameter was measured during a CSPC paradigm. Stimuli were randomly presented in either a mostly compatible location or a mostly incompatible location. Replicating prior research, the CSPC effect was found. The novel finding was that pupil diameter was greater in the mostly incompatible location compared to the mostly compatible location, despite participants' lack of awareness of context-specific task demands. Additionally, this difference occurred regardless of trial type or a preceding switch in location. These patterns support the view that context (location) dictates selection of optimal attentional settings in the CSPC paradigm, and varying levels of effort and performance accompany these settings. Theoretically, these patterns imply that cognitive control may operate fast, flexibly, and outside of awareness, but not effortlessly. (PsycINFO Database Record

Transfer of location-specific control to untrained locations

Recent research highlights a seemingly flexible and automatic form of cognitive control that is triggered by potent contextual cues, as exemplified by the location-specific proportion congruence effect--reduced compatibility effects in locations associated with a high as compared to low likelihood of conflict. We investigated just how flexible location-specific control is by examining whether novel locations effectively cue control for congruency-unbiased stimuli. In two experiments, biased (mostly compatible or mostly incompatible) training stimuli appeared in distinct locations. During a final block, unbiased (50% compatible) stimuli appeared in novel untrained locations spatially linked to biased locations. The flanker compatibly effect was reduced for unbiased stimuli in novel locations linked to a mostly incompatible compared to a mostly compatible location, indicating transfer. Transfer was observed when stimuli appeared along a linear function (Experiment 1) or in rings of a bullseye (Experiment 2). The novel transfer effects imply that location-specific control is more flexible than previously reported and further counter the complex stimulus-response learning account of location-specific proportion congruence effects. We propose that the representation and retrieval of control settings in untrained locations may depend on environmental support and the presentation of stimuli in novel locations that fall within the same categories of space as trained locations.

When does the test-study-test sequence optimize learning and retention?

In educational learning contexts, unlike typical contemporary laboratory paradigms, students have repeated opportunities to study and learn target material, thereby potentially allowing different sequences of testing and studying. We investigated learning and retention after several plausible sequences that were patterned on a classic memory paradigm. After initially reading a research methods text, 2 days later in 1 condition participants repeatedly restudied the material 3 times (SSS), in another condition they engaged in a test-restudy-test sequence (TST), and in a third condition participants repeatedly tested on the studied material (3 times: TTT). Participants received a final test 5 days later. In Experiment 1, both TST and TTT produced better final performance than did SSS; however, TST was not better than TTT. In Experiment 2 the TST condition was altered so that after the first test, correct/incorrect feedback was provided and the test and feedback were available during the study phase. With this protocol, TST produced better learning and retention than did TTT or SSS. These findings suggest possible critical aspects regarding test feedback and the availability of previous tests for helping students to optimize their restudy efforts after low- or no-stakes quizzes.

The curious case of orthographic distinctiveness: Disruption of categorical processing

How does orthographic distinctiveness affect recall of structured (categorized) word lists? On one theory, enhanced item-specific information (e.g., more distinct encoding) in concert with robust relational information (e.g., categorical information) optimally supports free recall. This predicts that for categorically structured lists, orthographically distinct (OD) word lists should be recalled better than orthographically common (OC) word lists. Another possibility is that OD items produce a far-reaching impairment in relational processing, including that of categorical information. This view anticipates an advantage in recall for OC items relative to OD lists. In Experiment 1 categorically structured OC lists produced better recall performance and higher clustering than did categorically structured OD lists. When words were presented in capital letters, thereby minimizing orthographic distinctiveness, OC and OD lists showed equivalent recall and category clustering (Experiment 2). When recall was cued with category labels, OC items were still better recalled than OD items (Experiment 3). These patterns, along with category access and items-per-category recalled, are consistent with the interpretation that orthographic distinctiveness creates a disruption in encoding of inter-item associations within a category. This interpretation expands previous work indicating that orthographic distinctiveness disrupts encoding of serial order information, another kind of inter-item association. (PsycINFO Database Record

Effects of cognitive training with and without aerobic exercise on cognitively demanding everyday activities

We investigated the potential benefits of a novel cognitive-training protocol and an aerobic exercise intervention, both individually and in concert, on older adults' performances in laboratory simulations of select real-world tasks. The cognitive training focused on a range of cognitive processes, including attentional coordination, prospective memory, and retrospective-memory retrieval, processes that are likely involved in many everyday tasks, and that decline with age. Primary outcome measures were 3 laboratory tasks that simulated everyday activities: Cooking Breakfast, Virtual Week, and Memory for Health Information. Two months of cognitive training improved older adults' performance on prospective-memory tasks embedded in Virtual Week. Cognitive training, either alone or in combination with 6 months of aerobic exercise, did not significantly improve Cooking Breakfast or Memory for Health Information. Although gains in aerobic power were comparable with previous reports, aerobic exercise did not produce improvements for the primary outcome measures. Discussion focuses on the possibility that cognitive-training programs that include explicit strategy instruction and varied practice contexts may confer gains to older adults for performance on cognitively challenging everyday tasks.

Evidence for the sparing of reactive cognitive control with age

The dual mechanisms of control account posited two qualitatively different cognitive control mechanisms (Braver, Gray, & Burgess, 2007). Proactive control is a sustained and capacity-demanding mechanism that is used to prevent interference, whereas reactive control acts transiently, poststimulus onset, to resolve interference. Prior research has demonstrated age-related deficits in proactive control, including in conflict tasks. However, few studies have examined the putative sparing of reactive control with age, and the purpose of this study was to fill that gap. In Experiment 1, older adults, like young adults, showed less interference for mostly incongruent items than mostly congruent items in a picture-word Stroop task, and this pattern extended to novel, 50% congruent transfer items. In Experiment 2, flanker stimuli in one screen location (or color) were mostly congruent whereas flanker stimuli in a second location (or color) were mostly incongruent. Young and older adults demonstrated context-specific proportion congruence effects, showing less interference in the mostly incongruent as compared to mostly congruent context for the location cue but not the color cue. These findings provide converging evidence for the intact and flexible use of reactive control with age, and challenge the view that aging is associated with a general deficit in cognitive control.

Conflict-triggered top-down control: default mode, last resort, or no such thing?

The conflict monitoring account posits that globally high levels of conflict trigger engagement of top-down control; however, recent findings point to the mercurial nature of top-down control in high conflict contexts. The current study examined the potential moderating effect of associative learning on conflict-triggered top-down control engagement by testing the Associations as Antagonists to Top-Down Control (AATC) hypothesis. In 4 experiments, list-wide proportion congruence was manipulated, and conflict-triggered top-down control engagement was examined by comparing interference for frequency-matched, 50% congruent items across mostly congruent (low conflict) and mostly incongruent (high conflict) lists. Despite the fact that global levels of conflict were varied identically across experiments, evidence of conflict-triggered top-down control engagement was selective to those experiments in which responses could not be predicted on the majority of trials via simple associative learning, consistent with the AATC hypothesis. In a 5th experiment, older adults showed no evidence of top-down control engagement under conditions in which young adults did, a finding that refined the interpretation of the patterns observed in the prior experiments. Collectively, these findings suggest that top-down control engagement in high conflict contexts is neither the default mode nor an unused (or nonexistent) strategy. Top-down control is best characterized as a last resort that is engaged when reliance on one's environment, and in particular associative responding, is unproductive for achieving task goals.

Controlling intentions: the surprising ease of stopping after going relative to stopping after never having gone

Decades of cognitive-control research have highlighted the difficulty of controlling a prepotent response. We examined whether having prepotent prospective-memory intentions similarly heightens the difficulty associated with stopping an intention once a prospective-memory task is finished. In three experiments, participants encoded a prospective-memory intention (e.g., press Q in response to the targets corn and dancer) and subsequently encountered either four targets or zero targets. Instructions then indicated that the prospective-memory task was finished. In a follow-up task, the targets appeared, and commission errors were recorded. Surprisingly, it was easier for participants to stop the intention when it had been fulfilled (four-target condition) than when it had gone unfulfilled (zero-target condition; Experiments 1 and 2). This was true even after intention cancellation (Experiment 2). Although repeatedly performing an intention strengthens target-action links, it appears to enable deactivation of the intention, a process that is largely target specific (Experiment 3). We relate these findings to the Zeigarnik effect, target-action deactivation, and reconsolidation theories.

Failing to forget: prospective memory commission errors can result from spontaneous retrieval and impaired executive control

Prospective memory (PM) research typically examines the ability to remember to execute delayed intentions but often ignores the ability to forget finished intentions. We had participants perform (or not perform; control group) a PM task and then instructed them that the PM task was finished. We later (re)presented the PM cue. Approximately 25% of participants made a commission error, the erroneous repetition of a PM response following intention completion. Comparisons between the PM groups and control group suggested that commission errors occurred in the absence of preparatory monitoring. Response time analyses additionally suggested that some participants experienced fatigue across the ongoing task block, and those who did were more susceptible to making a commission error. These results supported the hypothesis that commission errors can arise from the spontaneous retrieval of finished intentions and possibly the failure to exert executive control to oppose the PM response.

Exercise Engagement as a Moderator of the Effects of APOE Genotype on Amyloid Deposition

OBJECTIVE

APOE ε4 status has been associated with greater cortical amyloid deposition, whereas exercise has been associated with less in cognitively normal adults. The primary objective here was to examine whether physical exercise moderates the association between APOE genotype and amyloid deposition in cognitively normal adults.

DESIGN

APOE genotyping data and answers to a questionnaire on physical exercise engagement over the last decade were obtained in conjunction with cerebrospinal fluid (CSF) samples and amyloid imaging with carbon 11-labeled Pittsburgh Compound B ([(11)C]PiB) positron emission tomography. Participants were classified as either low or high exercisers based on exercise guidelines of the American Heart Association.

SETTING

Knight Alzheimer's Disease Research Center at Washington University, St Louis, Missouri.

PARTICIPANTS

A total of 201 cognitively normal adults (135 of whom were women) aged 45 to 88 years were recruited from the Knight Alzheimer's Disease Research Center. Samples of CSF were collected from 165 participants. Amyloid imaging was performed for 163 participants.

RESULTS

APOE ε4 carriers evidenced higher [(11)C]PiB binding (P<.001) and lower CSF Aβ42 levels (P<.001) than did noncarriers. Our previous findings of higher [(11)C]PiB binding (P=.005) and lower CSF Aβ42 levels (P=.009) in more sedentary individuals were replicated. Most importantly, we observed a novel interaction between APOE status and exercise engagement for [(11)C]PiB binding (P=.008) such that a more sedentary lifestyle was significantly associated with higher [(11)C]PiB binding for ε4 carriers (P=.013) but not for noncarriers (P=.20). All findings remained significant after controlling for age; sex; educational level; body mass index; the presence or history of hypertension, diabetes mellitus, heart problems, or depression; and the interval between assessments.

CONCLUSION

Collectively, these results suggest that cognitively normal sedentary APOE ε4-positive individuals may be at augmented risk for cerebral amyloid deposition.

Dissociating Levels of Cognitive Control

Attention is often imperfect; cognitive control is needed to counteract the tendency to attend to distractors that are incompatible with current goals. Cognitive psychologists have long explored cognitive control by examining Stroop interference—the slowed naming of colors on incongruent trials (e.g., “RED” displayed in blue ink), as compared to congruent trials (e.g., “RED” displayed in red ink), in the color-word Stroop task. The magnitude of interference reflects the effectiveness of cognitive control, but it does not reveal the precise processes used to minimize attention to the distracting word. The need for experimental approaches that accomplish this objective is underscored by the existence of qualitatively different cognitive control processes. Prior accounts stressed the use of top-down filtering processes at a task- or list-wide level to avoid word reading, but recent findings have shown that control of word reading is sometimes stimulus-driven—that is, triggered by the processing of stimuli or stimulus features. In this article, I highlight the critical findings that dissociate top-down and stimulus-driven control in the Stroop task, dissociations that are central to the view that cognitive control operates at multiple levels.

In Support of a Distinction between Voluntary and Stimulus-Driven Control: A Review of the Literature on Proportion Congruent Effects

Cognitive control is by now a large umbrella term referring collectively to multiple processes that plan and coordinate actions to meet task goals. A common feature of paradigms that engage cognitive control is the task requirement to select relevant information despite a habitual tendency (or bias) to select goal-irrelevant information. At least since the 1970s, researchers have employed proportion congruent (PC) manipulations to experimentally establish selection biases and evaluate the mechanisms used to control attention. PC manipulations vary the frequency with which irrelevant information conflicts (i.e., is incongruent) with relevant information. The purpose of this review is to summarize the growing body of literature on PC effects across selective attention paradigms, beginning first with Stroop, and then describing parallel effects in flanker and task-switching paradigms. The review chronologically tracks the expansion of the PC manipulation from its initial implementation at the list-wide level, to more recent implementations at the item-specific and context-specific levels. An important theoretical aim is demonstrating that PC effects at different levels (e.g., list-wide vs. item or context-specific) support a distinction between voluntary forms of cognitive control, which operate based on anticipatory information, and relatively automatic or reflexive forms of cognitive control, which are rapidly triggered by the processing of particular stimuli or stimulus features. A further aim is to highlight those PC manipulations that allow researchers to dissociate stimulus-driven control from other stimulus-driven processes (e.g., S-R responding; episodic retrieval). We conclude by discussing the utility of PC manipulations for exploring the distinction between voluntary control and stimulus-driven control in other relevant paradigms.

Cognitive and neural correlates of aerobic fitness in obese older adults

BacKGROUND/STUDY CONTEXT: Aerobic fitness is associated with preserved cognition and brain volume in older adulthood. The current study investigated whether the benefits of aerobic fitness extend to obese older adults, a segment of the population that is rapidly growing and who exhibit compromised cognition and brain structure relative to their nonobese counterparts.

METHODS

Measures of obesity, aerobic fitness, cognition (processing speed, executive function, spatial ability, memory), and regional brain volumes (prefrontal gray, prefrontal white, hippocampus) were obtained from 19 obese older adults aged 65 to 75. Hierarchical linear regression analyses were conducted to examine the proportion of unique variance in cognitive and volumetric measures accounted for by aerobic fitness after controlling for covariates (age, gender, and waist circumference).

RESULTS

Aerobic fitness accounted for a significant amount of unique variance in processing speed (adjusted R (2) = .44), executive function (adjusted R (2) = .34), and hippocampal volume (adjusted R (2) = .27).

CONCLUSION

This novel pattern of results suggests that obesity does not preclude the benefits of fitness for cognition and brain volume in older adults. Fitness appears to be a beneficial factor for maintenance of processing speed, executive function, and hippocampal volume, which are vulnerable to age- and/or obesity-related decline.

Memory Training Interventions: What has been forgotten?

Memory training for older adults often produces gains that are limited to the particular memory tasks encountered during training. We suggest that memory training programs may be misguided by an implicit "generalist" assumption-memory training on a couple of memory tasks will have a positive benefit on memory ability in general. One approach to increase memory-training benefits is to target training for the everyday memory tasks for which older adults struggle. Examples include training retrieval strategies, prospective memory strategies, and strategies for learning and remembering names. Another approach is to design training to foster transfer. Possible elements to improve transfer are increasing the variation that is experienced during the course of training at the level of stimuli and tasks, incorporating "homework" that guides the older adult to become attuned to situations in which the strategies can be applied, and providing older adults with a better understanding of how memory works. Finally, incorporating aerobic exercise into memory training programs may potentiate the acquisition and maintenance of the trained cognitive strategies.

Revealing list-level control in the Stroop task by uncovering its benefits and a cost

Interference is reduced in mostly incongruent relative to mostly congruent lists. Classic accounts of this list-wide proportion congruence effect assume that list-level control processes strategically modulate word reading. Contemporary accounts posit that reliance on the word is modulated poststimulus onset by item-specific information (e.g., proportion congruency of the word). To adjudicate between these accounts, we used novel designs featuring neutral trials. In two experiments, we showed that the list-wide proportion congruence effect is accompanied by a change in neutral trial color-naming performance. Because neutral words have no item-specific bias, this pattern can be attributed to list-level control. Additionally, we showed that list-level attenuation of word reading led to a cost to performance on a secondary prospective memory task but only when that task required processing of the irrelevant, neutral word. These findings indicate that the list-wide proportion congruence effect at least partially reflects list-level control and challenge purely item-specific accounts of this effect.

The moderating role of exercise on stress-related effects on the hippocampus and memory in later adulthood

OBJECTIVE

Chronic stress has well-documented negative effects on hippocampal structure and function, and has been suggested to contribute to age-related declines. In contrast, there is evidence that exercise has beneficial effects in older adults. The current investigation examined effects of lifetime stress on hippocampal volume and memory, the moderating role of stress on age effects, and the moderating role of exercise on stress-related effects.

METHOD

Measures of lifetime stress, exercise engagement, magnetic-resonance-imaging-based volumes, and cognitive performance were obtained in a sample of healthy middle-aged and older adults.

RESULTS

There was a significant negative influence of stress on hippocampal volume. In addition, exercise engagement moderated effects of lifetime stress on both hippocampal volume and memory. Specifically, lower exercise engagement individuals evidenced greater stress-related declines compared with high exercise engagement individuals.

CONCLUSIONS

These novel findings suggest that benefits of exercise in later adulthood may extend to minimizing detrimental effects of stress on the hippocampus and memory.