Preparing for perception and action (II): Automatic and effortful processes in response cueing

Chord skill: learning optimized hand postures and bimanual coordination

This reaction time study tested the hypothesis that in the case of finger movements skilled motor control involves the execution of learned hand postures. After delineating hypothetical control mechanisms and their predictions an experiment is described involving 32 participants who practiced 6 chord responses. These responses involved the simultaneous depression of one, two or three keys with either four right-hand fingers or two fingers of both hands. After practicing each of these responses for 240 trials, the participants performed the practiced and also novel chords with the familiar and with the unfamiliar hand configuration of the other practice group. The results suggest that participants learned hand postures rather than spatial or explicit chord representations. Participants practicing with both hands also developed a bimanual coordination skill. Chord execution was most likely slowed by interference between adjacent fingers. This interference seemed eliminated with practice for some chords but not for others. Hence, the results support the notion that skilled control of finger movements is based on learned hand postures that even after practice may be slowed by interference between adjacent fingers.

Proactive motor control within and between hands: Effects of age, motor set, and cue type

Several studies have reported that proactive motor control in a cued four-finger choice reaction task proceeds more efficiently with a 2-hands motor set (two fingers on each hand) than with a 1-hand motor set (four fingers on one hand). According to the Grouping Model, this is because the 2-hands motor set recruits distinct left and right hand representations located in separate cerebral hemispheres, whereas the 1-hand motor set recruits partially overlapping neural areas grouped together in one hemisphere. The latter neural organization increases neuromotor noise, thereby complicating proactive motor selection. The present study examined the effect of older age on the 2-hands motor selection advantage. A group of young and a group of older adults performed two proactive motor tasks-the procue task and the anticue task-with two motor sets: a 2-hands and 1-hand set. Predictive cues preceded the target signal at five different time intervals (100-850 ms), allowing advance selection of 2 out of 4 fingers. Older adults showed longer reaction times and smaller cueing benefits compared to younger adults. Overall, cueing benefits were greater, and accrued faster, with the 2-hands than with the 1-hand motor set, reflecting the beneficial impact of the neuroanatomical hand distinction. Importantly, the 2-hands advantage was substantially greater in the older age group, suggesting that the hand distinction might abate age-related neural dedifferentiation. These findings highlight the impact of cortical representational distinctiveness in proactive motor control, especially in older age.

Task structure boundaries affect response preparation

Does cognitive control operate globally (across task sets) or locally (within a task set)? Recently, two of the current co-authors (Hazeltine and Schumacher 2016; Schumacher and Hazeltine 2016) proposed that humans represent tasks as task files: hierarchically structured, compartmentalized subsets of our current goals and motivations, task instructions, and relevant stimuli and responses that are selected during task performance according to associated contextual rules. Here, we hypothesize that these task representations bound the implementation of cognitive control at distinct levels of this hierarchical structure. To investigate how task structure influences the implementation of control processes, we conducted a pair of experiments that utilized a precuing procedure. To manipulate task structure, we gave participants mappings in which two stimulus sets were either mapped so that each set was separated by response hand or both sets were interleaved across hands. In Experiment 1, participants responded to sets of images distinguished by their semantic category; in Experiment 2, they responded to sets based on different perceptual features (viz., location or color). During each experiment, precues could give information about the stimulus category or response hand for the upcoming target. The results indicate that participants with separated mappings represented the task hierarchically, while those with interleaved mappings did not. This pattern was consistent across experiments, despite the differences in the way that each set of stimuli influenced representation of the low-level task features. These findings suggest that task structure can be represented hierarchically, and that this structure supports distinct cognitive control processes at different hierarchical levels.

Foresight beats hindsight: The neural correlates underlying motor preparation in the pro-/anti-cue paradigm

BACKGROUND

Human motor behaviors are characterized by both, reactive and proactive mechanisms. Yet, studies investigating the neural correlates of motor behavior almost exclusively focused on reactive motor processes. Here, we employed the pro-/anti-cue motor preparation paradigm to systematically study proactive motor control in an imaging environment. In this paradigm, either pro- or anti-cues are presented in a blocked design. Four fingers (two from each hand) are mapped onto four visual target locations. Visual targets require a speeded response by one corresponding finger, but, most importantly, they are preceded by visual cues that are congruent ("pro-cue"), incongruent ("anti-cue"), or neutral with respect to the responding hand. With short cue-target intervals, congruence effects are based on automatic motor priming of the correct hand (in case of pro-cues) or incorrect hand (in case of anti-cues), generating, respectively, reaction time benefits or reaction time costs relative to the neutral-cue. With longer cue-target intervals, slower top-down processes become effective, transforming early anti-cue interference into late anti-cue facilitation.

METHODS

We adapted this paradigm to be compatible with neuroimaging, tested and validated it behaviorally-both inside and outside the imaging environment-and implemented it in a whole-brain functional magnetic resonance imaging study.

RESULTS AND CONCLUSION

Our imaging results indicate that pro-cues elicited much less neural activation than did anti-cues, the latter recruiting well-known cognitive top-down networks related to attention, response inhibition, and error monitoring/signaling, thereby revealing high-level influences on proactive motor processes.

Spatial Coding as a Function of Handedness and Responding Hand: Theoretical and Methodological Implications

The Simon effect shows that choice reactions are faster if the location of the stimulus and the response correspond, even when stimulus location is task-irrelevant. The Simon effect raises the question of what factors influence spatial coding. Until now, the effects of handedness, responding hand, and visual field were addressed in separate studies that used bimanual and unimanual tasks, providing inconclusive results. Here we aimed to close this empirical gap by looking at the effects of these variables in the same study. We used a unimanual version of a Simon task with four groups of participants: left-handed and right-handed, responding with the dominant or nondominant hand. Our results show that the Simon effect is substantially reduced in the field of the responding hand for all groups of participants, except for left-handed individuals responding with the left-hand. These findings highlight the importance of attention mechanisms in stimulus-response coding. They reflect that stimulus-response interference is influenced by hierarchical activation of response units. At a practical level, these findings call for a number of methodological considerations (e.g., handedness, responding hand, and visual field) when using stimulus-response conflict to address spatial coding and cognitive control functions in neurological populations.

Switch hands! Mapping temporal dynamics of proactive manual control with anticues

This study uses a novel behavioral paradigm-the anticue task-to investigate the temporal dynamics of proactive control aimed at the resolution of response conflict in the manual motor system. The anticue task is a 4-choice reaction time (RT) task, with left and right anticues indicating mirror-symmetrical response hands. In particular, anticues require participants to prepare fingers on the hand opposite to the side of the cue (counter-corresponding mapping), which contrasts with the more standard procues that prompt participants to prepare fingers on the hand spatially in line with the cue (corresponding mapping). In Experiment 1, we examined the effects of anticues and procues as a function of cue-target interval (range: 100-850ms). Results showed that procues produced RT benefits (relative to neutral cues), which increased with longer cue-target intervals. Anticues, however, produced RT costs with short cue-target intervals and RT benefits with longer cue-target intervals. These findings support the view that anticues are mediated by a time-consuming, proactive control process that, using inhibition and activation, redirects the initial but wrong activation of the ipsilateral hand to the correct contralateral hand. In Experiment 2, we used a simple detection response to test, and reject, an alternative (attentional) account of these findings. Theoretical and practical implications are discussed in the context of dual-route models of response selection, the activation-suppression model, and related experimental protocols such as antisaccade, Simon, Stroop, Eriksen flanker, and task switching paradigms.

Contingent capture of involuntary visual attention interferes with detection of auditory stimuli

The involuntary capture of attention by salient visual stimuli can be influenced by the behavioral goals of an observer. For example, when searching for a target item, irrelevant items that possess the target-defining characteristic capture attention more strongly than items not possessing that feature. Such contingent capture involves a shift of spatial attention toward the item with the target-defining characteristic. It is not clear, however, if the associated decrements in performance for detecting the target item are entirely due to involuntary orienting of spatial attention. To investigate whether contingent capture also involves a non-spatial interference, adult observers were presented with streams of visual and auditory stimuli and were tasked with simultaneously monitoring for targets in each modality. Visual and auditory targets could be preceded by a lateralized visual distractor that either did, or did not, possess the target-defining feature (a specific color). In agreement with the contingent capture hypothesis, target-colored distractors interfered with visual detection performance (response time and accuracy) more than distractors that did not possess the target color. Importantly, the same pattern of results was obtained for the auditory task: visual target-colored distractors interfered with sound detection. The decrement in auditory performance following a target-colored distractor suggests that contingent capture involves a source of processing interference in addition to that caused by a spatial shift of attention. Specifically, we argue that distractors possessing the target-defining characteristic enter a capacity-limited, serial stage of neural processing, which delays detection of subsequently presented stimuli regardless of the sensory modality.

Response-repetition effects depend on motor set: evidence for anatomical coding in response selection

Successful motor performance requires a process of response selection that chooses the correct response out of a set of possible ones. Most theories of response selection assume that this selection process operates on spatial codes, which define the location of stimuli and responses in environmental coordinates, with little or no role for the anatomical codes of the effectors involved. In this study, we tested this assumption by investigating response-repetition effects in a response-cuing paradigm using two motor sets (fingers on one hand vs. fingers on two hands). Reaction time results demonstrated a robust response-repetition benefit that was greater for the one-hand set than for the two-hands set. Furthermore, with the one-hand set the repetition benefit was independent of cue type and cue-stimulus interval on the previous trial, whereas with the two-hands set it was strongly modulated by these two factors. These differential response-repetition effects for one- and two-hands motor sets demonstrate the important role of the neuro-anatomical hand distinction in response selection, thereby supporting multiple coding notions.

Response preparation in Parkinson's disease: automatic vs. controlled processing

Using a finger cuing paradigm, we investigated response preparation in Parkinson's disease (PD). The central question was whether PD individuals are differentially affected by preparatory cues that specify a more automatic response set configuration (that induces within-hand preparation) as opposed to a more controlled one (that induces between-hands preparation). Reaction times (RTs) and error rates were measured in 20 non-demented individuals with PD and 20 healthy control participants with a long and short preparation interval (500 ms and 2000 ms). RT benefits and/or costs were measured for cues indicating a within- and between-hands motor preparatory set. Overall, RTs were significantly longer, and errors more frequent, for PD participants than for control participants. More importantly, in comparison with control subjects, PD individuals showed a significant deficit in between-hands preparation but not in within-hand preparation. Furthermore, longer preparation intervals slowed down cued RTs of the control participants, but not those of the PD individuals. Together, these findings suggest that whereas automatic response preparation processes are spared in PD, controlled response preparation processes operate at a slower rate and/or are delayed in time.

Response-level probability effects on reaction time: now you see them, now you don't

Many reaction time (RT) experiments have tested for response-level probability effects. Their results have been mixed, which is surprising because psychophysiological studies provide clear evidence of motor-level changes associated with an anticipated response. A survey of the designs used in the RT studies reveals many potential problems that could conceal the effects of response probability. We report five new RT experiments testing for response-level probability effects with the most promising of the previous designs-that of Blackman ( 1972 )-and with new designs. Some of these experiments yield evidence of response-level probability effects, but others do not. It appears that response-level probability effects are present primarily in simple tasks with a strong emphasis on response preparation, possibly because participants only expend effort on response preparation in these tasks.

Grouping mechanisms in response preparation investigated with event-related brain potentials

Preliminary information about responses facilitates performance, especially when the information can be grouped into stimulus-response sets, for example, into fingers belonging to the same hand. Here, we studied the mechanisms of supposedly fast and automatic exogenous as compared to slow and controlled endogenous grouping of same-hand fingers. As compared to endogenous cuing, exogenous cuing facilitated reaction times and induced larger amplitudes of the contingent negative variation, but did not show any advantage in amplitude or latency of the lateralized readiness potential or in the magnitude of current source density over the motor cortices. Similarly, the stimulus preceding negativity did not seem to be a plausible explanation for the observed effect. Therefore, at least one functional mechanism underlying exogenous stimulus-response grouping appears to be the facilitation of central response programming.

Spared within-hands but impaired between-hands response preparation in aging

OBJECTIVES

Older people can use advance information to prepare a subset of finger responses. It is debated, however, whether aging affects the preparation of finger responses on two hands (between-hands preparation) more strongly than the preparation of finger responses on one hand (within-hands preparation). The present study examined the role of temporal uncertainty in this issue.

METHODS

We asked a group of young and older participants to perform a finger-cuing task with four preparation intervals (2, 3, 4, and 5 s), presented either separately in distinct blocks of trials (fixed design: no temporal uncertainty) or randomly intermixed across trials (mixed design: temporal uncertainty).

RESULTS

Reaction time and error rates revealed age equivalence for within-hands preparation but an age-related difference for between-hands preparation, regardless of how the preparation intervals were presented.

DISCUSSION

These findings demonstrate a robust, structural difference in the maximal preparation benefit that older adults can achieve when preparing two fingers on two hands but not on one hand. These outcomes are discussed in terms of several theories of cognitive aging.

Oculomotor interference during manual response preparation: evidence from the response-cueing paradigm

Preparation provided by visual location cues is known to speed up behavior. However, the role of concurrent saccades in response to visual cues remains unclear. In this study, participants performed a spatial precueing task by pressing one of four response keys with one of four fingers (two of each hand) while eye movements were monitored. Prior to the stimulus, we presented a neutral cue (baseline), a hand cue (corresponding to left vs. right positions), or a finger cue (corresponding to inner vs. outer positions). Participants either remained fixated on a central fixation point or moved their eyes freely. The results demonstrated that saccades during the cueing interval altered the pattern of cueing effects. Finger cueing trials in which saccades were spatially incompatible (vs. compatible) with the subsequently required manual response exhibited slower manual RTs. We propose that interference between saccades and manual responses affects manual motor preparation.

The influence of response grouping on free-choice decision making in a response selection task

Previous research has demonstrated an advantage for the preparation of fingers on one hand over the preparation of fingers on two hands, and for the preparation of homologous fingers over that of non-homologous fingers. In the present study, we extended the precuing effects observed with finger responses to response selection under free-choice conditions. Participants were required to choose from a range of possible responses following the presentation of a precue that indicated which response to prepare (go-to precue) or prevent (no-go-to precue). In Experiment 1 the choice was between homologous and non-homologous finger responses on the hand opposite to the precue while in Experiment 2 the choice was between finger responses on the same or different hand to the precue. In the go-to precue condition, the frequency of homologous finger choices was more frequent than non-homologous finger responses. Similarly, participants chose finger responses on the same hand as the precue regardless of whether they were instructed to prepare or prevent the precued response. The hand effect bias was stronger than the finger effect bias. These findings are consistent with the Grouping Model (Adam, Hommel, & Umilta, 2003).

Response preparation with static and moving hands: differential effects of unimanual and bimanual movements

This study investigated the effects of uni- and bimanual hand movements on the efficiency of within- and between-hands response preparation in a spatial cuing task. Predictions were derived from the Grouping Model of finger preparation, inspired by insights from neurophysiology (i.e., the concepts of transcollosal facilitation and cognitive overruling of basic neural coordination patterns). Sixteen participants performed the finger cuing task with one, two, or no hand(s) moving. Reaction time results revealed that unimanual and bimanual hand movements had similar effects on within-hand preparation but differential effects on between-hands preparation. This finding demonstrates a strong dissociation between within- and across-hands finger preparation, suggesting distinct underlying mechanisms as hypothesized by the Grouping Model.

Automatic sequential response priming and intentional response preparation in choice reaction tasks: evidence from response repetition and response cuing

This study examined the interaction of response repetition and response cuing in a finger cuing task with a short and a long cue-stimulus interval (CSI). We observed shorter reaction times (RTs) with increasing CSI and a substantial response repetition benefit. However, this benefit was abolished at the long CSI, suggesting that response cuing neutralized the repetition effect. According to additive-factors logic, the observed interaction suggests that both repetition and cuing exert their influence on a common processing stage, which we identify as the response selection stage. We argue that cuing and repetition effects are expressions of distinct mental operations: cuing is based on intentional response code activation, whereas repetition is based on sequential, automatic response code priming. Cue-based intentional code activation starts slowly and increases with CSI, but sequential response priming is independent of CSI, explaining why cuing abolishes the response repetition benefit at the long CSI.

Movement planning and reprogramming in individuals with autism

Two experiments explored how individuals with and without autism plan and reprogram movements. Participants were given partial or complete information regarding the location of the upcoming manual movement. In Experiment 1, direct information specified the hand or direction of the upcoming movement. These results replicated previous reports that participants with autism utilize advance information to prepare their movements in the same manner as their chronologically age matched peers. Experiment 2 examined how individuals respond to an unexpected change in the movement requirements. Participants received advance information about the hand and direction of the upcoming movement. On 20% of the trials participants needed to adjust either the hand or direction they had prepared. Overall, the individuals with autism had difficulty reprogramming already planned movements, particularly if a different effector was required.

Motor set modulates automatic priming effects of uninformative cues

In a series of three experiments, we examined facilitatory and inhibitory effects of uninformative spatial cues in a four-choice reaction time (RT) task that required three different types of responses: detection, reaching, and keypressing. Results revealed a pattern of facilitation and inhibition that strongly depended on response mode: Whereas detection and reaching showed longer RTs for cued than uncued locations (reflecting inhibition of return), keypress responses showed shorter RTs for cued than uncued locations (reflecting automatic response activation). Together, these results provide converging evidence for the Grouping model of precuing effects [Adam, J. J., Hommel, B., & Umiltà, C. (2003). Preparing for perception and action (I): The role of grouping in the response-cuing task. Cognitive Psychology, 46, 302-358; Adam, J. J., Hommel, B., & Umiltà, C. (2005). Preparing for perception and action (II): Automatic and effortful processes in response-cuing. Visual Cognition, 12, 1444-1473].

Cue validity effects in response preparation: a pupillometric study

This study examined the effects of cue validity and cue difficulty on response preparation to provide a test of the Grouping Model [Adam, J.J., Hommel, B. and Umiltà, C., 2003. Preparing for perception and action (I): the role of grouping in the response-cuing paradigm. Cognit. Psychol. 46(3), 302-58, Adam, J.J., Hommel, B. and Umiltà, C., 2005. Preparing for perception and action (II) automatic and effortful processes in response cuing. Vis. Cogn. 12(8), 1444-1473.]. We used the pupillary response to index the cognitive processing load during and after the preparatory interval (2 s). Twenty-two participants performed the finger-cuing tasks with valid (75%) and invalid (25%) cues. Results showed longer reaction times, more errors, and larger pupil dilations for invalid than valid cues. During the preparation interval, pupil dilation varied systematically with cue difficulty, with easy cues (specifying 2 fingers on 1 hand) showing less pupil dilation than difficult cues (specifying 2 fingers on 2 hands). After the preparation interval, this pattern of differential pupil dilation as a function of cue difficulty reversed for invalid cues, suggesting that cues which incorrectly specified fingers on one hand required more effortful reprogramming operations than cues which incorrectly specified fingers on two hands. These outcomes were consistent with predictions derived from the Grouping Model. Finally, all participants exhibited two distinct pupil dilation strategies: an "early" strategy in which the onset of the main pupil dilation was tied to onset of the cue, and a "late" strategy in which the onset of the main pupil dilation was tied to the onset of the target. Thus, whereas the early pupil dilation strategy showed a strong dilation during the preparation interval, the late pupil strategy showed a strong constriction. Interestingly, only the late onset pupil dilation strategy revealed the above reported sensitivity to cue difficulty, showing for the first time that the well-known pupil's sensitivity to task difficulty can also emerge when the pupil is constricting instead of dilating.

Preparation for horizontal or vertical dimensions affects the right-left prevalence effect

When stimulus and response simultaneously vary in both horizontal and vertical dimensions, the stimulus-response compatibility effect is often larger for the horizontal dimension. We investigated the role of preparation for each dimension in this right-left prevalence. In Experiment 1, tasks based on horizontal and vertical dimensions were mixed in random order, and the relevant dimension in each trial was cued with a variable cue-target stimulus onset asynchrony (SOA). A right-left prevalence effect was observed only when participants prepared for the upcoming task. Experiment 2 replicated the absence of the prevalence effect for the simultaneous presentation of cue and target using a fixed SOA of 0 msec. In Experiment 3, the right-left prevalence emerged with a 0-msec SOA when participants prepared for e achdimension basedon its frequency. These resultssuggest that participants' internal set can be greater for the horizontal dimension, leading to the right-left prevalence effect.

Response preparation with static versus moving hands

This research tested the response inhibition account of the hand-advantage found in the finger pre-cuing task. According to this account, the advantage of preparing two fingers on one hand (represented in one hemisphere) as opposed to preparing two fingers on two hands (represented in two hemispheres) is due, in part, to a response inhibition process that operates more efficiently within than between hemispheres. In this view, supplying extra activation to both hemispheres by moving the hands should decrease the within-hemisphere inhibition advantage. Twelve participants performed the finger pre-cuing task with static and moving hands. As predicted by the response inhibition account, the hand-advantage, present with the hands at rest, decreased with the hands moving.

Distinct mechanisms for planning keypress and reaching responses: A developmental study

This study examined developmental effects in the ability to use precue information for the planning of keypress and reaching responses. Participants from four age groups (7, 9, 13, and 21 year olds) performed a spatial precuing task either by pressing one of four response keys (keypress task) or by reaching directly toward one of the four target locations on the screen (reaching task). Reaction time data revealed striking age differences in the ability to use advance information in the keypress task, not in the reaching task. This dissociation confirms the hypothesis that distinct and separate mechanisms govern the planning of indirect keypress and direct reaching responses.