Issues and trends in the debate on discrete vs. continuous processing of information

C-SMB 2.0: Integrating over 25 years of motor sequencing research with the Discrete Sequence Production task

An exhaustive review is reported of over 25 years of research with the Discrete Sequence Production (DSP) task as reported in well over 100 articles. In line with the increasing call for theory development, this culminates into proposing the second version of the Cognitive framework of Sequential Motor Behavior (C-SMB 2.0), which brings together known models from cognitive psychology, cognitive neuroscience, and motor learning. This processing framework accounts for the many different behavioral results obtained with the DSP task and unveils important properties of the cognitive system. C-SMB 2.0 assumes that a versatile central processor (CP) develops multimodal, central-symbolic representations of short motor segments by repeatedly storing the elements of these segments in short-term memory (STM). Independently, the repeated processing by modality-specific perceptual and motor processors (PPs and MPs) and by the CP when executing sequences gradually associates successively used representations at each processing level. The high dependency of these representations on active context information allows for the rapid serial activation of the sequence elements as well as for the executive control of tasks as a whole. Speculations are eventually offered as to how the various cognitive processes could plausibly find their neural underpinnings within the intricate networks of the brain.

The basis of S-R learning: associations between individual stimulus features and responses

Three experiments tested the hypothesis that response selection skill involves associations between individual stimulus features and responses. The Orientation group in Experiments 1 and 2 first practiced responding to the orientation of a line stimulus while ignoring its color, and the Color group practiced responding to the color of the line while disregarding its orientation. When in the ensuing test conditions the Orientation group responded to the color of the line, RTs and errors increased when the then irrelevant line orientation was inconsistent with practice. This confirmed that during practice, Orientation participants had developed orientation feature-response associations they could not fully inhibit. Yet, evidence for color feature-response associations was not observed in the Color group. This was attributed to orientation identification being faster than color identification, even after having practiced responding to colors. Experiment 3 involved practicing to three line stimuli with unique orientation and color combinations. It showed evidence for the independent development of orientation feature-response associations and color feature-response associations. Together, these results indicate that the typical RT reduction with practice in response selection tasks is caused in part by the capacity of participants to learn selecting responses on the basis of the stimulus feature that becomes available first.

Assessment of the psychomotor fitness level of cadet pilots after a 6-month flight training period - pilot study

Objectives

The aim of the study was to investigate the impact of 6-month aviation practice on the improvement of physical fitness and cognitive abilities of cadet pilots.

Materials and methods

Twenty cadet pilots (men) with an average age of 22 from the Polish Air Force Academy were tested. Two tests of effort were conducted: before (test I) and after (test II) practical flights. Test of physical effort relyed on the number of rotations of looping accomplished. When performing rotations on looping, in tests I and II, the percentage level of task performance was assessed using a diagnostic and training device. Tasks for the exerciser were sent wirelessly to the glasses from the operator’s position. The heart rate (HR) and blood pressure were measured with a camera-type Microlife AG.

Results

In test II, there was a statistically significant improvement in the percentage of task completion (p < 0.01) and an insignificant improvement in the performance of rotations on looping compared to test I. After Test I and II demonstrated a statistically significant increase in HR and systolic blood pressure when compared to before test values. Test II illustrated a significant decrease in systolic blood pressure after effort (p < 0.05) with regard to test I.

Conclusion

The study showed that cadet aviation practice ameliorated their physical fitness and cognitive skills, as well as helped to diminish their situational stress, which resulted in a decrease in systolic blood pressure after test II.

Perception and action as viewed from the Theory of Event Coding: a multi-lab replication and effect size estimation of common experimental designs

The Theory of Event Coding (TEC) has influenced research on action and perception across the past two decades. It integrates several seminal empirical phenomena and it has continued to stimulate novel experimental approaches on the representational foundations of action control and perceptual experience. Yet, many of the most notable results surrounding TEC originate from an era of psychological research that relied on rather small sample sizes as judged by today's standards. This state hampers future research aiming to build on previous phenomena. We, therefore, provide a multi-lab re-assessment of the following six classical observations: response-effect compatibility, action-induced blindness, response-effect learning, stimulus-response binding, code occupation, and short-term response-effect binding. Our major goal is to provide precise estimates of corresponding effect sizes to facilitate future scientific endeavors. These effect sizes turned out to be considerably smaller than in the original reports, thus allowing for informed decisions on how to address each phenomenon in future work. Of note, the most relevant results of the original observations were consistently obtained in the present experiments as well.

Applying Heart Rate Variability to Monitor Health and Performance in Tactical Personnel: A Narrative Review

Human performance optimization of tactical personnel requires accurate, meticulous, and effective monitoring of biological adaptations and systemic recovery. Due to an increased understanding of its importance and the commercial availability of assessment tools, the use of heart rate variability (HRV) to address this need is becoming more common in the tactical community. Measuring HRV is a non-invasive, practical method for objectively assessing a performer's readiness, workload, and recovery status; when combined with additional data sources and practitioner input, it provides an affordable and scalable solution for gaining actionable information to support the facilitation and maintenance of operational performance. This narrative review discusses the non-clinical use of HRV for assessing, monitoring, and interpreting autonomic nervous system resource availability, modulation, effectiveness, and efficiency in tactical populations. Broadly, HRV metrics represent a complex series of interactions resulting from internal and external stimuli; therefore, a general overview of HRV applications in tactical personnel is discussed, including the influence of occupational specific demands, interactions between cognitive and physical domains, and recommendations on implementing HRV for training and recovery insights into critical health and performance outcomes.

Examining the Perceptual-Cognitive Mechanism of Deceptive Actions in Sports

In several kinds of sports, deceptive actions are used to hinder the anticipation performance of an opponent. During a head fake in basketball, a player turns the head to one side but passes the ball to the other side. A pass with a head fake generates a head-fake effect in the observer, which is characterized by slower and more error-prone responses to the pass direction as compared to passes without a head fake. Whereas the head-fake effect has been replicated several times, the question of its origin with dynamic stimuli has not been answered yet. The present study includes four experiments, which are conducted to examine the perceptual-cognitive mechanism underlying the effect by using the model of dimensional overlap (Kornblum et al., 1990) and the additive factors logic (Sternberg, 1969). Results point to multiple processes contributing to the head-fake effect for dynamic stimuli, which operate not only at a perceptual level but also at a level of response selection.

The arrow of time: Advancing insights into action control from the arrow version of the Eriksen flanker task

Since its introduction by B. A. Eriksen and C. W. Eriksen (Perception & Psychophysics, 16, 143-49, 1974), the flanker task has emerged as one of the most important experimental tasks in the history of cognitive psychology. The impact of a seemingly simple task design involving a target stimulus flanked on each side by a few task-irrelevant stimuli is astounding. It has inspired research across the fields of cognitive neuroscience, psychophysiology, neurology, psychiatry, and sports science. In our tribute to Charles W. ("Erik") Eriksen, we (1) review the seminal papers originating from his lab in the 1970s that launched the paradigmatic task and laid the foundation for studies of action control, (2) describe the inception of the arrow version of the Eriksen flanker task, (3) articulate the conceptual and neural models of action control that emerged from studies of the arrows flanker task, and (4) illustrate the influential role of the arrows flanker task in disclosing developmental trends in action control, fundamental deficits in action control due to neuropsychiatric disorders, and enhanced action control among elite athletes.

The Effects of Major Depressive Disorder on the Sequential Organization of Information Processing Stages: An Event-Related Potential Study

The adverse effects of depression on patients’ life have been reported but information about its effects on the sequential organization of the information processing stages remains poorly understood as previous studies focused only on distinct stages. This study adds to existing knowledge by examining the effect of major depressive disorder (MDD) on the sequential organization of information processing, executive and community functioning. Fifty-seven participants with 19 participants each for first episode depression (FMDD), recurrent episodes depression (RMDD), and healthy controls (HCs) participated in this study. They completed assessments on executive and community functioning measures, and choice reaction time task (CRTT) for the event-related potential (ERP) data. Findings revealed no significant between-group difference in executive functioning but participants with depression (FMDD and RMDD) were found to be more depressed, with FMDD participants having worse community functioning skills compared with HCs. There was no significant between-group main effect on behavioral data. ERP data showed significantly less positive-going P3b among RMDD participants compared with HCs. FMDD participants used a different information processing strategy at P1, while HCs and RMDD participants used a different processing strategy at N2b compared with the other group(s), respectively. The results suggest the use of multifaceted assessment to get a holistic view of the health status of people with MDD in order to inform clinicians on the appropriate interventional strategies needed for the patient.

The Causal Role of the Lateral Prefrontal Cortex for Task-order Coordination in Dual-task Situations: A Study with Transcranial Magnetic Stimulation

Dual tasks are characterized by the requirement for additional task-order coordination processes that schedule the processing order of two temporally overlapping tasks. Preliminary evidence from functional imaging studies suggests that lateral pFC (lPFC) activation correlates with implementing these task-order coordination processes. However, so far, it is unclear whether the lPFC is also causally involved in coordinating task order during dual-task performance and which exact mechanisms are implemented by this brain region. In this study, we addressed these open issues by applying online TMS during a dual-task situation. For this purpose, participants performed a dual task in fixed-order blocks with a constant order of tasks and in random-order block, in which the order of tasks varied randomly and thus demands on task-order coordination were increased. In Experiment 1, TMS of the lPFC compared with control TMS conditions impaired dual-task performance in random-order blocks, whereas performance in fixed-order blocks was unaffected by TMS. In Experiment 2, we tested for the specificity of the lPFC TMS effect on task-order coordination by applying TMS over the preSMA. We showed that preSMA TMS did not affect dual-task performance, neither in fixed-order nor in random-order blocks. Results of this study indicate that the lPFC, but not the preSMA, is causally involved in implementing task-order coordination processes in dual-task situations.

Associating Vehicles Automation With Drivers Functional State Assessment Systems: A Challenge for Road Safety in the Future

In the near future, vehicles will gradually gain more autonomous functionalities. Drivers' activity will be less about driving than about monitoring intelligent systems to which driving action will be delegated. Road safety, therefore, remains dependent on the human factor and we should identify the limits beyond which driver's functional state (DFS) may no longer be able to ensure safety. Depending on the level of automation, estimating the DFS may have different targets, e.g., assessing driver's situation awareness in lower levels of automation and his ability to respond to emerging hazard or assessing driver's ability to monitor the vehicle performing operational tasks in higher levels of automation. Unfitted DFS (e.g., drowsiness) may impact the driver ability respond to taking over abilities. This paper reviews the most appropriate psychophysiological indices in naturalistic driving while considering the DFS through exogenous sensors, providing the more efficient trade-off between reliability and intrusiveness. The DFS also originates from kinematic data of the vehicle, thus providing information that indirectly relates to drivers behavior. The whole data should be synchronously processed, providing a diagnosis on the DFS, and bringing it to the attention of the decision maker in real time. Next, making the information available can be permanent or intermittent (or even undelivered), and may also depend on the automation level. Such interface can include recommendations for decision support or simply give neutral instruction. Mapping of relevant psychophysiological and behavioral indicators for DFS will enable practitioners and researchers provide reliable estimates, fitted to the level of automation.

Small is beautiful: In defense of the small-N design

The dominant paradigm for inference in psychology is a null-hypothesis significance testing one. Recently, the foundations of this paradigm have been shaken by several notable replication failures. One recommendation to remedy the replication crisis is to collect larger samples of participants. We argue that this recommendation misses a critical point, which is that increasing sample size will not remedy psychology's lack of strong measurement, lack of strong theories and models, and lack of effective experimental control over error variance. In contrast, there is a long history of research in psychology employing small-N designs that treats the individual participant as the replication unit, which addresses each of these failings, and which produces results that are robust and readily replicated. We illustrate the properties of small-N and large-N designs using a simulated paradigm investigating the stage structure of response times. Our simulations highlight the high power and inferential validity of the small-N design, in contrast to the lower power and inferential indeterminacy of the large-N design. We argue that, if psychology is to be a mature quantitative science, then its primary theoretical aim should be to investigate systematic, functional relationships as they are manifested at the individual participant level and that, wherever possible, it should use methods that are optimized to identify relationships of this kind.

Evidence for distinct steps in response preparation from a delayed response paradigm

Task parameters still affect reaction times even when all necessary information for executing an action is presented prior to a Go signal to execute the action. Hypotheses in terms of short-term memory capacity, residual activation, and a separate motor-programming stage have been suggested to explain what can and cannot be prepared prior to a delayed Go signal. To test these hypotheses, we used a delayed response task, in which participants were to initiate a movement at onset of an imperative Go signal following the target stimulus. Across Experiments 1-3 we varied task properties including stimulus type, information uncertainty and response complexity, respectively, while controlling other factors. We also varied the time available to process the response by randomly varying the interval between onset of the target and the Go signal (i.e., the stimulus onset asynchrony, or SOA). If the preparation process is completed before initiation, the examined factor should display a strong interaction with SOA, with its effect disappearing at long SOAs. Our results showed strong, weaker, and no interaction patterns for the three factors, respectively, favoring the separate stage hypothesis, according to which response preparation is separated into steps to arrange kinematic specifications into muscle-controllable terms.

Empathy for pain influences perceptual and motor processing: Evidence from response force, ERPs, and EEG oscillations

In the present study we investigated the nature and chronometry of empathy for pain influences on perceptual and motor processes. Thus, event-related brain potentials (ERPs), response force (RF) and oscillatory electroencephalography (EEG) activity were measured while participants were presented with pictures of body parts in painful or neutral situations. Their task consisted in either judging the painfulness of the stimuli or counting the body parts displayed. ERP results supported the assumption of an early automatic component of empathy for pain, as reflected by the early posterior negativity (EPN), and of a late controlled component, as reflected by the late posterior positivity (P3). RF indicated that empathy-evoking stimuli facilitate motor responses if attention is directed toward the pain dimension, whereas EEG oscillations in the mu-and beta-band revealed, independent of the task, an enhanced activation of the sensorimotor cortex after the response to painful compared to neutral stimuli. In conclusion, present findings indicate that empathy-evoking stimuli produce automatic and controlled effects on both perceptual and motor processing.

Effects of Mixed versus Blocked Design on Stimulus Evaluation: Combining Underadditive Effects

According to the asynchronous discrete coding model of Miller, two manipulations should display underadditive effects on reaction time if they slow down noncontingent stages associated with the processing of two separable dimensions of a stimulus. Under additive effects are also predicted by a dual route model when a task variable is factorially varied with design type (mixed vs blocked). Interpretations of both underadditive effects and their combination were evaluated. Intact and degraded stimuli were presented to 18 young adults either in a single block (mixed) or in separate blocks (blocked). Spatial stimulus-response (S-R) compatibility was manipulated in all conditions. Stimulus degradation and S-R compatibility interacted underadditively, but only in blocked presentations. Both interpretations of underadditive effects were supported. Eye-movement registrations provided additional support for the alternative routes model.

The interplay of goal-driven and stimulus-driven influences on spatial orienting

Search for a target stimulus among distractors is subject to both goal-driven and stimulus-driven influences. Variables that selectively modify these influences have shown strong interaction effects on saccade trajectories toward the target, suggesting the involvement of a shared spatial orienting mechanism. However, subsequent manual response times (RTs) have revealed additive effects, suggesting that different mechanisms are involved. In the present study, we tested the hypothesis that an interaction for RTs is obscured by preceding multisaccade trajectories, promoted by the continuous presence of distractors in the display. In two experiments, we compared a condition in which distractors were removed soon after the presentation of the search display to a standard condition in which distractors were not removed. The results showed additive goal-driven and stimulus-driven effects on RTs in the standard condition, but an interaction when distractors were removed. These findings support the view that both variables influence a shared spatial orienting mechanism.

The cost of errors: Perceived error detection in dual-task conditions

Detecting that an error has been made can be crucial for the implementation of appropriate behavioral adjustments. Brain imaging studies indicate that error detection is not limited to response errors and that similar mechanisms are engaged even when behavioral control is not needed. The current study examines whether perceived error detection - the detection of erroneous stimuli that violate our expectations - requires central resources. In two experiments - using a dual-task design - we show that perceived error detection in the first task creates a bottleneck in information processing and delays the response selection of the second task. The results suggest that the requirement for central cognitive resources is a general feature of error detection because it is present even when the demand for behavioral control is low.

Basics for sensorimotor information processing: some implications for learning

In sensorimotor activities, learning requires efficient information processing, whether in car driving, sport activities or human-machine interactions. Several factors may affect the efficiency of such processing: they may be extrinsic (i.e., task-related) or intrinsic (i.e., subjects-related). The effects of these factors are intimately related to the structure of human information processing. In the present article we will focus on some of them, which are poorly taken into account, even when minimizing errors or their consequences is an essential issue at stake. Among the extrinsic factors, we will discuss, first, the effects of the quantity and quality of information, secondly, the effects of instruction and thirdly motor program learning. Among the intrinsic factors, we will discuss first the influence of prior information, secondly how individual strategies affect performance and, thirdly, we will stress the fact that although the human brain is not structured to function errorless (which is not new) humans are able to detect their errors very quickly and (in most of the cases), fast enough to correct them before they result in an overt failure. Extrinsic and intrinsic factors are important to take into account for learning because (1) they strongly affect performance, either in terms of speed or accuracy, which facilitates or impairs learning, (2) the effect of certain extrinsic factors may be strongly modified by learning and (3) certain intrinsic factors might be exploited for learning strategies.

The structure of motor programming: evidence from reaction times and lateralized readiness potentials

There is a widely accepted notion that movement elements are assembled prior to movement execution in a central motor programming stage. However, it is not clear how this stage is structured-whether it is a unitary stage allowing different motor parameters to cross talk or whether there are several independent processes dealing with each motor parameter. We addressed this question by orthogonally manipulating two movement-related factors: response sequence complexity and movement duration. Both factors yielded main effects on reaction time but no interaction. Additive effects of both factors on the onsets of response- but not stimulus-synchronized lateralized readiness potentials suggest separable motoric loci of sequence complexity and duration. These findings are at variance with the notion of a unitary movement programming stage.

Conflict tasks and the diffusion framework: Insight in model constraints based on psychological laws

Formal models of decision-making have traditionally focused on simple, two-choice perceptual decisions. To date, one of the most influential account of this process is Ratcliff's drift diffusion model (DDM). However, the extension of the model to more complex decisions is not straightforward. In particular, conflicting situations, such as the Eriksen, Stroop, or Simon tasks, require control mechanisms that shield the cognitive system against distracting information. We adopted a novel strategy to constrain response time (RT) models by concurrently investigating two well-known empirical laws in conflict tasks, both at experimental and modeling levels. The two laws, predicted by the DDM, describe the relationship between mean RT and (i) target intensity (Piéron's law), (ii) standard deviation of RT (Wagenmakers-Brown's law). Pioneering work has shown that Piéron's law holds in the Stroop task, and has highlighted an additive relationship between target intensity and compatibility. We found similar results in both Eriksen and Simon tasks. Compatibility also violated Wagenmakers-Brown's law in a very similar and particular fashion in the two tasks, suggesting a common model framework. To investigate the nature of this commonality, predictions of two recent extensions of the DDM that incorporate selective attention mechanisms were simulated and compared to the experimental results. Both models predict Piéron's law and the violation of Wagenmakers-Brown's law by compatibility. Fits of the models to the RT distributions and accuracy data allowed us to further reveal their relative strengths and deficiencies. Combining experimental and computational results, this study sets the groundwork for a unified model of decision-making in conflicting environments.

Response-specific slowing in older age revealed through differential stimulus and response effects on P300 latency and reaction time

Older age produces numerous changes in cognitive processes, including slowing in the rate of mental processing speed. There has been controversy over the past three decades about whether this slowing is generalized or process-specific. A growing literature indicates that it is process-specific and suggests it is most dramatic at the interface where a stimulus input is translated into a response output. We tested this hypothesis using a task in which young and older adult males made either compatible or incompatible responses to the word LEFT or RIGHT shown briefly and variously located in a 4 row × 6 column matrix surrounded by # signs or by letters chosen randomly from the sets A-G or A-Z. Processing speed was measured using P300 latency and reaction time. Experimental effects on these two measures provided support for the hypothesis in revealing that stimulus identification processes were preserved, whereas processes related to translating a stimulus input into a designated response output and then selecting that response were compromised in the elderly.

Evidence for graded central processing resources in a sequential movement task

In the present experiment, we examined slowing of the individual key presses of a familiar keying sequence by four different versions of a concurrent tone counting task. This was done to determine whether the same cognitive processor that has previously been assumed by the dual processor model (DPM) to initiate familiar keying sequences and assist in their execution, is involved also in the central processes of a very different task (viz. identifying tones and counting target tones). The present results confirm this hypothesis. They also suggest that in this particular situation the central processing resources underlying the cognitive processor can be distributed across the central processes of different tasks in a graded manner, rather than that they continue to behave like a single, central processor that serially switches between the central processes of the concurrently performed tasks. We argue that the production of highly practiced movement sequences can be considered automatic in the sense that execution of familiar movement sequences can continue without cognitive control once they have been initiated.

Representing serial action and perception

This article presents a review on the representational base of sequence learning in the serial reaction time task. The first part of the article addresses the major questions and challenges that underlie the debate on implicit and explicit learning. In the second part, the informational content that underlies sequence representations is reviewed. The latter issue has produced a rich and equivocal literature. A taxonomy illustrates that substantial support exists for associations between successive stimulus features, between successive response features, and between successive response-to-stimulus compounds. We suggest that sequence learning is not predetermined with respect to one particular type of information but, rather, develops according to an overall principle of activation contingent on task characteristics. Moreover, substantiating such an integrative approach is proposed by a synthesis with the dual-system model (Keele, Ivry, Mayr, Hazeltine, & Heuer, 2003).

The real-time link between person perception and action: brain potential evidence for dynamic continuity

Using event-related potentials, we investigated how the brain extracts information from another's face and translates it into relevant action in real time. In Study 1, participants made between-hand sex categorizations of sex-typical and sex-atypical faces. Sex-atypical faces evoked negativity between 250 and 550 ms (N300/N400 effects), reflecting the integration of accumulating sex-category knowledge into a coherent sex-category interpretation. Additionally, the lateralized readiness potential revealed that the motor cortex began preparing for a correct hand response while social category knowledge was still gradually evolving in parallel. In Study 2, participants made between-hand eye-color categorizations as part of go/no-go trials that were contingent on a target's sex. On no-go trials, although the hand did not actually move, information about eye color partially prepared the motor cortex to move the hand before perception of sex had finalized. Together, these findings demonstrate the dynamic continuity between person perception and action, such that ongoing results from face processing are immediately and continuously cascaded into the motor system over time. The preparation of action begins based on tentative perceptions of another's face before perceivers have finished interpreting what they just saw.

Visual sensory processing deficit in the occipital region in children with attention-deficit / hyperactivity disorder as revealed by event-related potentials during cued continuous performance test

AIMS OF THE STUDY

Recent studies described several changes of attention-related components of late frontal event-related potentials (ERPs) during Go/NoGo paradigm in children with attention-deficit/hyperactivity disorder (ADHD). We aimed to determine whether ERP components corresponding to earlier encoding of visual incoming information are also modulated by attentional disorders.

METHODS

We recorded high-resolution EEG in 15 children meeting DSM-IV criteria for ADHD, comprising 15 age-matched control groups during an equiprobable Go/NoGo task in a cued continuous performance test (CPT-AX) paradigm. Both P100 and N200 ERP components were measured in response to both Go and NoGo stimuli. We analyzed both components with SwLORETA in order to localize their brain sources.

RESULTS

A low rate of Go correct response and high rate of omission errors were observed in ADHD children. When compared to controls, these displayed delayed P100 and N200 latency, and lower P100-NoGo amplitude. In addition, the P100 latency was delayed for NoGo compared to Go condition. The source of P100 was located in occipital area. A sizable decrease in early electrical activity was found in ADHD, especially in the NoGo condition.

CONCLUSION

Our results suggest an early deficit in visual sensory integration within the occipital cortex in children with ADHD.

Remembered but unused: the accessory items in working memory that do not guide attention

If we search for an item, a representation of this item in our working memory guides attention to matching items in the visual scene. We can hold multiple items in working memory. Do all these items guide attention in parallel? We asked participants to detect a target object in a stream of objects while they maintained a second item in memory for a subsequent task. On some trials, we presented this memory item as a distractor in the stream. Subjects did not confuse these memory items with the search target, as the false alarm rate on trials where the memory item was presented in the stream was comparable to that on trials with only regular distractors. However, a comparable performance does not exclude that the memory items are processed differently from normal distractors. We therefore recorded event-related potentials (ERPs) evoked by search targets, memory items, and regular distractors. As expected, ERPs evoked by search targets differed from those evoked by distractors. Search targets elicited an occipital selection negativity and a frontal selection positivity indexing selective attention, whereas the P3b component, which reflects the matching of sensory events to memory representations, was enhanced for targets compared to distractors. Remarkably, the ERPs evoked by memory items were indistinguishable from the ERPs evoked by normal distractors. This implies that the search target has a special status in working memory that is not shared by the other items. These other, "accessory" items do not guide attention and are excluded from the matching process.

Short Article: Why do we slow down after an error? Mechanisms underlying the effects of posterror slowing

People often become slower in their performance after committing an error, which is usually explained by strategic control adjustments towards a more conservative response threshold. The present study tested an alternative hypothesis for explaining posterror slowing in terms of behavioural interferences resulting from error monitoring by manipulating stimulus contrast and categorization difficulty in a choice reaction time task. The response–stimulus interval (RSI) was either short or long, using a between-subject (Experiment 1) and a within-subject design (Experiment 2). Posterror slowing was larger and posterror accuracy lower in short than in long RSI situations. Effects of stimulus contrast disappeared in posterror trials when RSI was short. At long RSIs, stimulus contrast was additive with posterror slowing. The results support the idea that at least two mechanisms contribute to posterror slowing: a capacity-limited error-monitoring process with the strongest influence at short RSIs and a criterion adjustment mechanism at longer RSIs.

Lengthening fixed preparatory foreperiod durations within a digit magnitude classification task serves mainly to shift distributions of response times upwards

In this study, the effect of lengthening foreperiod duration (i.e. the time between the presentation of a warning signal and a subsequent target stimulus) on choice RTs is examined. The foreperiod durations used were either 2 or 8s and were fixed within pure blocks of trials. The task was to determine whether a single-digit target stimulus was either smaller or larger than 5 and responses were provided manually. An additive relation between foreperiod duration length and numerical distance from 5 was present in the mean RTs. Subsequent ex-Gaussian analyses of the shapes of the RT distributions indicated that they become shifted upwards as the foreperiod increased with relatively smaller increases in the sizes of their tails. It is argued mainly that the latter finding is incompatible with the strategic time estimation view of the fixed foreperiod duration effect.

Acute aerobic exercise and information processing: energizing motor processes during a choice reaction time task

The immediate and short-term after effects of a bout of aerobic exercise on young adults' information processing were investigated. Seventeen participants performed an auditory two-choice reaction time (RT) task before, during, and after 40 min of ergometer cycling. In a separate session, the same sequence of testing was completed while seated on an ergometer without pedalling. Results indicate that exercise (1) improves the speed of reactions by energizing motor outputs; (2) interacts with the arousing effect of a loud auditory signal suggesting a direct link between arousal and activation; (3) gradually reduces RT and peaks between 15 and 20 min; (4) effects on RT disappear very quickly after exercise cessation; and (5) effects on motor processes cannot be explained by increases in body temperature caused by exercise. Taken together, these results support a selective influence of acute aerobic exercise on motor adjustment stage.

Persistent neurocognitive problems after adjuvant chemotherapy for breast cancer

BACKGROUND

Neurocognitive problems have been observed in a number of women previously treated with adjuvant chemotherapy for breast cancer. The present study aims to combine the results of neuropsychological and electrophysiological techniques collected in patients with breast cancer treated with cyclophosphamide/methotrexate/5-fluorouracil (CMF) at different time points.

PATIENTS AND METHODS

Patients with breast cancer treated with adjuvant CMF chemotherapy (n = 63) were examined with neuropsychological tests 1 year after treatment and compared with healthy women (n = 60; T1 portion of the study). Based on neuropsychological test performance, patients were classified as cognitively impaired or unimpaired. Four years later, behavioral and neurophysiological measures (T2 portion of the study) were collected during an information-processing task in a subgroup of patients (n = 26). At T2, we compared the results of cognitively impaired patients (n = 8) with those of patients classified as cognitively unimpaired at T1 (n = 18).

RESULTS

In the initial neuropsychological assessment, 33.3% of the patients were classified as cognitively impaired, compared with 10% of healthy women. At T2, impaired patients who received CMF showed longer P3 latencies, lower P3 amplitudes, longer reaction times, and made more errors in an information processing task compared with unimpaired patients who received CMF.

CONCLUSION

The results indicate the persistence of neurocognitive problems < or = 5 years after completion of chemotherapy and consistency across different assessment techniques.

Effects of response sequence length on motor programming: a chronometric analysis

The present experiment studied choice response context effects on the programming of response sequences using behavioural and electrophysiological methods. Participants were asked to produce responses differing in sequence length (1-key vs. 3-key responses) with either their left or right hand in a choice reaction time (RT) task. The choice response context was manipulated by a blocked or mixed execution of 1-key and 3-key responses. A sequence length effect on RT was observed in the blocked but not in the mixed condition. The time course of the lateralized readiness potential indicates a motoric locus of the sequence length effect, suggesting that the response hand is activated before the entire motor program is established.

Control over speeded actions: a common processing locus for micro- and macro-trade-offs?

Cognitive control processes associated with long- and short-term adjustments of human behaviour have attracted much interest recently. It is still unclear, however, whether the mechanisms underlying these adjustments share a common locus within the chain of stimulus-response processing. In order to address this issue, the present study employed a speed-accuracy instruction producing a macro-trade-off, whereas micro-trade-off was studied by means of posterror slowing in reaction time (RT). Participants performed a spatially compatible or incompatible four-stimuli-to-two-response alternative choice RT task. Reliable variations in micro-and macro-trade-off as well as effects of spatial compatibility were found in RT and error rate. Most importantly, posterror slowing was larger when instruction stressed accuracy rather than speed, an effect being independent of spatial compatibility. Because the influence of speed-accuracy instruction and posterror slowing on performance was strongest for response alternations, together present findings suggest that the mechanisms underlying micro- and macro-trade-offs have one common locus at the level of motor processing. Additional influences of macro-trade-off on premotoric processing are likely.

Interaction between location- and frequency-based inhibition of return in human auditory system

Using a cue-target paradigm, this study investigated the interaction between location and frequency information processing in human auditory inhibition of return (IOR). The cue and the target varied in terms of location and frequency and participants were asked to perform a target detection, localization or frequency discrimination task. Results showed that, when neither location nor frequency of auditory stimuli was particularly relevant to the target detection task, there was a location-based IOR only if the cue and the target were identical in frequency and there was a frequency-based IOR only if the cue and the target were presented at the same location. When a particular feature of auditory stimuli, whether location or frequency, was directly relevant to the current task, the IOR effect was evident for this feature only if the cue and the target differed on the task-irrelevant feature, while the IOR effect was eliminated for the task-relevant feature when the cue and the target had the same task-irrelevant feature. Similarly, the IOR effect based on the task-irrelevant feature was evident when the cue and the target differed on the task-relevant feature, and was eliminated or reversed when the cue and the target shared the task-relevant feature. Theoretical implications of these findings for auditory IOR are discussed.