Suppressing visual feedback in written composition: Effects on processing demands and coordination of the writing processes

The goal of this experiment was to investigate the role of visual feedback during written composition. Effects of suppression of visual feedback were analyzed both on processing demands and on on‐line coordination of low‐level execution processes and of high‐level conceptual and linguistic processes. Writers composed a text and copied it either with or without visual feedback. Processing demands of the writing processes were evaluated with reaction times to secondary auditory probes, which were analyzed according to whether participants were handwriting (in a composing and a copying task) or engaged in high‐level processes (when pausing in a composing task). Suppression of visual feedback increased reaction time interference (secondary reaction time minus baseline reaction time) during handwriting in the copying task and not during pauses in the composing task. This suggests that suppression of visual feedback only affected processing demands of execution processes and not those of high‐level conceptual and linguistic processes. This is confirmed by analysis of the quality of the texts produced by participants, which were little, if at all, affected by the suppression of visual feedback. Results also indicate that the increase in processing demands of execution related to suppression of visual feedback affected on‐line coordination of the writing processes. Indeed, when visual feedback was suppressed, reaction time interferences associated with handwriting were not reliably different in the copying task or the composing task but were significantly different when visual feedback was not suppressed: They were lower in the copying task than in the composition task. When visual feedback was suppressed, writers activated step‐by‐step execution processes and high‐level writing processes, whereas they concurrently activated these writing processes when composing with visual feedback.     

The involvement of the orbitofrontal cortex in learning under changing task contingencies

Previous investigations examining the rat prefrontal cortex subregions in attentional-set shifting have commonly employed two-choice discriminations. To better understand how varying levels of difficulty influence the contribution of the prefrontal cortex to learning, the present studies examined the effects of orbitofrontal cortex inactivation in a two- or four-choice odor reversal learning test. Long-Evans rats were trained to dig in cups that contained distinct odors. In the two-choice odor discrimination, one odor cup was always associated with a cereal reinforcement in acquisition while the opposite odor cup was associated with a cereal reinforcement in reversal learning. In the four-choice odor discrimination, an additional two cups containing distinct odors were used that were never associated with reinforcement in acquisition or reversal learning. Bilateral infusions of the GABA-A agonist, muscimol (0.5 microg) into the orbitofrontal cortex did not impair acquisition of either the two- or four-choice discrimination task. However, muscimol infusions into the orbitofrontal cortex impaired two- and four-choice reversal learning. In the two-choice odor reversal, muscimol treatment selectively increased perseverative errors. In the four-choice odor reversal, muscimol treatment increased perseverative, regressive, as well as irrelevant errors. These findings suggest that the orbital prefrontal cortex not only enables task switching by supporting the initial inhibition of a previously relevant choice pattern, but under increasing task demands also enables the reliable execution of a new choice pattern and reduction of interference to irrelevant stimuli.     

Context influences decision-making in boys with attention-deficit/hyperactivity disorder: A comparison of traditional and novel choice-impulsivity paradigms

Attention-deficit/hyperactivity disorder (ADHD) is characterized by an impaired ability to maintain attention and/or hyperactivity/impulsivity. Impulsivity is frequently defined as the preference for small, immediate rewards over larger, delayed rewards, and has been associated with a variety of negative outcomes such as risky behavior and academic difficulty. Extant studies have uniformly utilized the traditional paradigm of presenting two response choices, which limits the generalization of findings to scenarios in which children/adolescents are faced with dichotomous decisions. The current study is the first to examine the effect of manipulating the number of available response options on impulsive decision-making in boys with and without ADHD. A total of 39 boys (ADHD = 16, typically developing [TD] = 23) aged 8–12 years completed a traditional two-choice impulsivity task and a novel five-choice impulsivity task to examine the effect of manipulating the number of choice responses (two vs five) on impulsive decision-making. A five-choice task was utilized as it presents a more continuous array of choice options when compared to the typical two-choice task, and is comparable given its methodological similarity to the two-choice task. Results suggested that boys with ADHD were significantly more impulsive than TD boys during the two-choice task, but not during the five-choice task. Collectively, these findings suggest that ADHD-related impulsivity is not ubiquitous, but rather dependent on variation in demands and/or context. Further, these findings highlight the importance of examining ADHD-related decision-making within the context of alternative paradigms, as the exclusive utilization of two-choice tasks may promote inaccurate conceptualizations of the disorder.     

Sequential predictability effects on initiation time and movement time for adults and children

First-grade children and adults performed a two-choice initiation-time/ movement-time task in which signals were (a) more likely to repeat than alternate, (b) more likely to alternate than repeat or (c) equally likely to alternate or repeat. Sequential predictability influenced initiation time but not movement time for adults and for children. These results do not support the suggestion (Wickens, 1974) that sequential predictability affects initiation time and movement time for children but only initiation time for adults. Adults and first graders did differ in their response to repeated events. Adults averaged faster initiation time for alternated than repeated responses and children averaged faster initiation time for repeated than alternated responses.     

Dissociable stages of problem solving (I): temporal characteristics revealed by eye-movement analyses

Understanding the functional neuroanatomy of planning and problem solving may substantially benefit from better insight into the chronology of the cognitive processes involved. Based on the assumption that regularities in cognitive processing are reflected in overtly observable eye-movement patterns, here we recorded eye movements while participants worked on Tower of London (TOL) problems that comprised an experimental manipulation of different task demands. Single-trial saccade-locked analyses revealed that higher demands on forming an internal problem representation were associated with an increased number of gaze alternations between start state and goal state, but did not show any effect on the durations of these inspections of the states. In contrast, higher demands on actual planning in terms of mental manipulations of working memory contents coincided with a prolonged duration of the very last inspection of the start state (i.e., immediately preceding movement execution) but did not show any effect on the number of gaze alterations. Differential task demands on internalization and planning processes during problem solving hence selectively affect different eye-movement parameters. Moreover, these findings complement previous neuroimaging data on dissociable contributions of left and right dorsolateral prefrontal cortex in problem solving with novel evidence for a corresponding dissociation in the eye-movement patterns reflecting the associated cognitive processes.     

Attention and suppression affect tactile perception in reach-to-grasp movements

Reaching with the hand is characterized by a decrease in sensitivity to tactile stimuli presented to the moving hand. Here, we investigated whether tactile suppression can be canceled by attentional orienting. In a first experiment, participants performed a dual-task involving a goal-directed movement paired with the speeded detection of a tactile pulse. The pulse was either delivered to the moving or stationary hand, during movement preparation, execution, or the post-movement phase. Furthermore, stimulation was delivered with equal probability to either hand, or with a higher probability to either the moving or resting hand. The results highlighted faster RTs under conditions of higher probability of stimulation delivery to both moving and resting hands, thus indicating an attentional effect. For the motor preparation period, RTs were faster only at the resting hand under conditions where tactile stimulation was more likely to be delivered there. In a second experiment, a non-speeded perceptual task was used as a secondary task and tactile discrimination thresholds were recorded. Tactile stimulation was delivered concomitantly at both index fingers either in the movement preparation period (both before and after the selection of the movement effector had taken place), in the motor execution period, or, in a control condition, in the time-window of motor execution, but the movement of the hand was restrained. In the preparation period, tactile thresholds were comparable for the two timings of stimulation delivery; i.e., before and after the selection of the movement effector had taken place. These results therefore suggest that shortly prior to, and during, the execution of goal-directed movements, a combined facilitatory and inhibitory influence acts on tactile perception.     

Programming strategies for rapid aiming movements under simple and choice reaction time conditions

Increases in reaction time (RT) as a function of response complexity have been shown to differ between simple and choice RT tasks. Of interest in the present study was whether the influence of response complexity on RT depends on the extent to which movements are programmed in advance of movement initiation versus during execution (i.e., online). The task consisted of manual aiming movements to one or two targets (one- vs. two-element responses) under simple and choice RT conditions. The probe RT technique was employed to assess attention demands during RT and movement execution. Simple RT was greater for the two- than for the single-target responses but choice RT was not influenced by the number of elements. In both RT tasks, reaction times to the probe increased as a function of number of elements when the probe occurred during movement execution. The presence of the probe also caused an increase in aiming errors in the simple but not choice RT task. These findings indicated that online programming was occurring in both RT tasks. In the simple RT task, increased executive control mediated the integration between response elements through the utilization of visual feedback to facilitate the implementation of the second element.     

Programming strategies for rapid aiming movements under simple and choice reaction time conditions

Increases in reaction time (RT) as a function of response complexity have been shown to differ between simple and choice RT tasks. Of interest in the present study was whether the influence of response complexity on RT depends on the extent to which movements are programmed in advance of movement initiation versus during execution (i.e., online). The task consisted of manual aiming movements to one or two targets (one- vs. two-element responses) under simple and choice RT conditions. The probe RT technique was employed to assess attention demands during RT and movement execution. Simple RT was greater for the two- than for the single-target responses but choice RT was not influenced by the number of elements. In both RT tasks, reaction times to the probe increased as a function of number of elements when the probe occurred during movement execution. The presence of the probe also caused an increase in aiming errors in the simple but not choice RT task. These findings indicated that online programming was occurring in both RT tasks. In the simple RT task, increased executive control mediated the integration between response elements through the utilization of visual feedback to facilitate the implementation of the second element.     

The effect of state anxiety on the online and offline control of fast target-directed movements

In target-directed aiming, afferent information is used to adjust limb trajectories during movement execution (i.e. online) and to enhance the programming of subsequent trials (i.e. offline). The objective of the present study was to determine the influence of state anxiety on both online and offline afferent information processing for the first time. Participants practiced either a directional aiming task (Experiment 1) or an amplitude aiming task (Experiment 2) without anxiety before being transferred to a high anxiety condition. In both experiments, results revealed that anxiety resulted in a decrement in performance. Furthermore, use of afferent information to adjust movement trajectories online was disrupted when movements were performed with anxiety, whereas there were no differences in the offline processing of afferent information between the low anxiety and high anxiety conditions.     

Can actions affect perceptual processing?

Previous studies reported impairments in a perceptual task performed during the selection and execution of an action. These findings, however, always raise the question of whether the impairment actually reflects a reduction in perceptual sensitivity or whether it results only from an unspecific reduction in attentiveness given the perceptual task. Recent studies by the authors indicate that actions can also have a specific impact on perception in a dual-task situation. The identification of a left or right arrow is impaired when it appears during the execution of a compatible left or right keypress. In three experiments Signal Detection Theory is applied to test whether this impairment is also found in the sensitivity measure d' or whether it originates only from a response tendency. The results revealed a general lower d' for the identification of arrows that were compatible to simultaneously executed keypresses than for arrows that were incompatible. The bias measure c was small and/or did not differ between conditions. Additional analyses revealed that the impairment is due to a higher mean perceptual degradation of stimuli in the compatible condition and that it is restricted to the point in time when the central movement command is generated. Thus, actions actually seem able to affect perceptual processing.     

The effect of intentional expectancy on mental processing: a chronopsychophysiological investigation

Expected events are processed faster than unexpected ones. Previously, we have reported evidence that passive expectancies determined by the preceding event sequence mainly affected the duration of motoric processes. Here we examined the effects of instructed, intentional expectancies in a two-choice reaction time (RT) task. As predicted, RTs were shorter for expected than unexpected events. Onset of the lateralized readiness potential as an index of selective response activation, and the latency of the P300 component of the event-related potential, reflecting the duration of perceptual processing, indicated that intentional expectancy affected the time demands for central processing but did not influence the duration of early perceptual or motoric processes. Together the present and our previous results provide evidence that different kinds of expectancy can be distinguished by their locus of action within the information processing system.     

An analysis of performance by pre-school children on the KRISP and on a length discrimination task

The speed and accuracy of judgements made by pre-school children on the Kansas Reflection-Impulsivity Scale for Pre-schoolers (KRISP - Wright 1971, 1973) and on a two-choice length discrimination task were investigated. If subjects were relatively accurate on the KRISP then correct responses tended to be faster than errors while if subjects were relatively inaccurate errors were the faster. It is inferred that accurate subjects respond asymptotically in terms of a speed-accuracy tradeoff while inaccurate subjects set a less demanding criterion. Accurate subjects showed a tendency to increase inspection time as a function of item difficulty. This relation did not hold for inaccurate subjects.However, groups classified by means of the KRISP did not differ in either the speed of correct responses or accuracy of line length discriminations. For all groups judgement times were significantly related to stimulus differences and to stimulus ratios. There was no evidence that so-called impulsive children engage in less efficient and less detailed processing than other children.It is argued, contrary to the view of Kagan and his co-workers (e.g. Kakan 1966), that speed and accuracy of responding may not reflect a stable trait dimension. Rather children appear to be able to change their strategies according to the particular demands, implicit or explicit, of the task.     

The automaticity of complex motor skill learning as a function of attentional focus

The present experiment was designed to test the predictions of the constrained-action hypothesis. This hypothesis proposes that when performers utilize an internal focus of attention (focus on their movements) they may actually constrain or interfere with automatic control processes that would normally regulate the movement, whereas an external focus of attention (focus on the movement effect) allows the motor system to more naturally self-organize. To test this hypothesis, a dynamic balance task (stabilometer) was used with participants instructed to adopt either an internal or external focus of attention. Consistent with earlier experiments, the external focus group produced generally smaller balance errors than did the internal focus group and responded at a higher frequency indicating higher confluence between voluntary and reflexive mechanisms. In addition, probe reaction times (RTs) were taken as a measure of the attention demands required under the two attentional focus conditions. Consistent with the hypothesis, the external focus participants demonstrated lower probe RTs than did the internal focus participants, indicating a higher degree of automaticity and less conscious interference in the control processes associated with the balance task.     

Anxiety-induced changes in movement behaviour during the execution of a complex whole-body task.

We investigated the impact of anxiety on movement behaviour during the execution of a complex perceptual-motor task. Masters' (1992) conscious processing hypothesis suggests that under pressure an inward focus of attention occurs, resulting in more conscious control of the movement execution of well-learned skills. The conscious processes interfere with automatic task execution hereby inducing performance decrements. Recent empirical support for the hypothesis has focused on the effects of pressure on end performance. It has not been tested so far whether the changes in performance are also accompanied by changes in movement execution that would be expected following Masters' hypothesis. In the current study we tested the effects of anxiety on climbing movements on a climbing wall. Two identical traverses at different heights on a climbing wall provided different anxiety conditions. In line with the conscious processing hypothesis we found that anxiety had a significant effect on participants' movement behaviour evidenced by increases in climbing time and the number of explorative movements (Experiments 1 and 2) and by longer grasping of the holds and slower movements (Experiment 2). These results provide additional support for the conscious processing hypothesis and insight into the relation between anxiety, performance, and movement behaviour.     

The attentional cost of amplitude and directional requirements when pointing to targets

The aim of this study was to investigate the comparative cost of accuracy constraints in direction or amplitude for movement regulation. The attentional cost is operationally defined as the amount of disturbance created in a secondary task by the simultaneous execution of a pointing task in direction or amplitude. The cost is expressed in terms of modifications in response to a secondary task, consisting of a foot-pedal release in response to an auditory stimulus (probe). The probe was introduced during the programming portion or the first, middle, or last portion of the pointing movement. The independent variables were the requirements of the task: direction or amplitude, and the moments of occurrence of the probe. Subjects were submitted to eight experimental conditions: (1) simple foot reaction time to a buzzer; (2) single directional task; (3) single amplitude task; (4) dual directional task (i.e. directional task with probe); (5) dual amplitude task (i.e. amplitude task with probe); (6) retest of foot simple reaction time; (7) retest of single directional task; and (8) retest of single amplitude task. Regulation in direction was more attention-demanding than regulation in distance in terms of programming. During pointing in amplitude, probe RT increased monotonically from start to end of movement execution, whereas directional pointing did not lead to any significant probe RT changes. These results emphasize the specific attentional loads for directional and amplitude pointing tasks, hence the involvement of different central nervous system mechanisms for the programming and regulation of the directional and amplitude parameters of pointing movements.     

When the brain simulates stopping: Neural activity recorded during real and imagined stop-signal tasks

It has been suggested that mental rehearsal activates brain areas similar to those activated by real performance. Although inhibition is a key function of human behavior, there are no previous reports of brain activity during imagined response cancellation. We analyzed event-related potentials (ERPs) and time–frequency data associated with motor execution and inhibition during real and imagined performance of a stop-signal task. The ERPs characteristic of stop trials—that is, the stop-N2 and stop-P3—were also observed during covert performance of the task. Imagined stop (IS) trials yielded smaller stop-N2 amplitudes than did successful stop (SS) and unsuccessful stop (US) trials, but midfrontal theta power similar to that in SS trials. The stop-P3 amplitude for IS was intermediate between those observed for SS and US. The results may be explained by the absence of error-processing and correction processes during imagined performance. For go trials, real execution was associated with higher mu and beta desynchronization over motor areas, which confirms previous reports of lower motor activation during imagined execution and also with larger P3b amplitudes, probably indicating increased top-down attention to the real task. The similar patterns of activity observed for imagined and real performance suggest that imagination tasks may be useful for training inhibitory processes. Nevertheless, brain activation was generally weaker during mental rehearsal, probably as a result of the reduced engagement of top-down mechanisms and limited error processing.     

Effects of gonadectomy and androgen supplementation on attention in male rats

Androgens are hypothesized to enhance aspects of mnemonic processing. However, it is unclear whether the memory improvement is associated with changes in earlier aspects of information processing, such as attention. The present experiments examined the effects of gonadectomy or supplementation with testosterone or dihydrotestosterone on performance of male rats in a two-lever attention task that required discrimination of visual signals and non-signals. In Experiment 1, Long-Evans rats were trained in the attention task and then underwent gonadectomy or sham-surgery. Postsurgically, animals were tested for 20 sessions in the attention task and then received manipulations designed to increase attentional demands. Gonadectomized and sham-treated animals performed similarly during immediate postsurgical testing and across all manipulations. Finally, the effects of administering the muscarinic receptor antagonist scopolamine (0, 0.1, and 0.2 mg/kg) on attentional performance were assessed for all animals. Scopolamine decreased accuracy of signal detection but did not differentially affect gonadectomized and sham-treated animals. In Experiment 2, a new group of rats (not gonadectomized) was trained to perform the attention task and subsequently administered testosterone (0, 0.1, and 0.5 mg/kg) or dihydrotestosterone (0, 0.1, and 0.5mg/kg) prior to performing the standard version of the attention task and in the presence of a visual distractor. Testosterone (0.5 mg/kg) decreased accuracy on non-signal trials and, at 0.1 mg/kg, decreased latencies to retrieve a reward. Dihydrotestosterone (0.5 mg/kg) decreased accuracy on non-signal trials during visual distractor sessions. The present data do not support the hypothesis that alterations in attention critically mediate androgen-induced changes in mnemonic processing. Supra-physiological androgen levels appear to be capable of impairing attentional processing.     

Manual asymmetries in bimanual reaching: the influence of spatial compatibility and visuospatial attention

The goal of the present investigation was to explore the possible expression of hemispheric-specific processing during the planning and execution of a bimanual reaching task. Participants (N = 9) completed 80 bimanual reaching movements (requiring simultaneous, bilateral production of arm movements) to peripherally presented targets while selectively attending to either their left or right hand. Further, targets were presented in spatially compatible (ipsilateral to the aiming limb) and incompatible (contralateral to the aiming limb) response contexts. It was found that the left hand exhibited temporal superiority over the right hand in the response planning phase of bimanual reaching, indicating a left hand/right hemisphere advantage in the preparation of a bimanual response. During response execution, and consistent with the view that interhemispheric processing time (Barthelemy & Boulinguez, 2002) or biomechanical constraints (Carey, Hargreaves, & Goodale, 1996) generate temporal delays, longer movement times were observed in response to spatially incompatible target positions. However, no hemisphere-specific benefit was demonstrated for response execution. Based on these findings, we propose lateralized processing is present at the time of response planning (i.e., left hand/right hemisphere processing advantage); however, lateralized specialization appears to be annulled during dynamic execution of a bimanual reaching task.     

Factors that affect action possibility judgements: Recent experience with the action and the current body state

It has been suggested that action possibility judgements are formed through a covert simulation of the to-be-executed action. We sought to determine whether the motor system (via a common coding mechanism) influences this simulation, by investigating whether action possibility judgements are influenced by experience with the movement task (Experiments 1 and 2) and current body states (Experiment 3). The judgement task in each experiment involved judging whether it was possible for a person's hand to accurately move between two targets at presented speeds. In Experiment 1, participants completed the action judgements before and after executing the movement they were required to judge. Results were that judged movement times after execution were closer to the actual execution time than those prior to execution. The results of Experiment 2 suggest that the effects of execution on judgements were not due to motor activation or perceptual task experience—alternative explanations of the execution-mediated judgement effects. Experiment 3 examined how judged movement times were influenced by participants wearing weights. Results revealed that wearing weights increased judged movement times. These results suggest that the simulation underlying the judgement process is connected to the motor system, and that simulations are dynamically generated, taking into account recent experience and current body state.     

Cognitive processes in writing during pause and execution periods

The present study investigated how writing processes are activated during pause and execution periods. In two experiments, handwriting demands were manipulated by asking participants to compose with their familiar handwriting or with a high-demanding cursive uppercase calligraphy. Experiment 1 investigated narrative writing, a task with low planning demands. Experiment 2 addressed essay writing, a task with stronger planning demands. Occurrences of processes and their cognitive effort were analysed by asking participants to respond to random auditory probes and then to report their ongoing mental activity according to learned categories referring to the planning, translating, and revising writing processes. All together, the findings indicate that demands on planning did not affect how writing processes were activated during pauses and execution periods but automaticity of handwriting did. When handwriting was effortless, translating was mostly activated in parallel with motor execution, whereas revising and planning were mainly activated during pauses. However, none of the writing processes could be characterised as being typical of pauses, since translating was activated to a similar extent as the other two processes. By contrast, when handwriting was effortful, participants shifted to a more sequential functioning and activated translating mainly during pauses.