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.     

Effects of sleep loss, time of day, and extended mental work on implicit and explicit learning of sequences

Tacit knowledge is part of many professional skills and can be studied experimentally with implicit-learning paradigms. The authors explored the effects of 2 different stressors, loss of sleep and mental fatigue, on implicit learning in a serial-response time (RT) task. In the 1st experiment, 1 night of sleep deprivation was shown to impair implicit but not explicit sequence learning. In the 2nd experiment, no impairment of both types of sequence learning was found after 1.5 hr of mental work. Serial-RT performance, in contrast, suffered from both stressors. These findings suggest that sleep deprivation induces specific risks for automatic, skill-based behavior that are not present in consciously controlled performance.     

Implicit and explicit learning of event sequences: evidence for distinct coding of perceptual and motor representations

Event-related brain potentials (ERPs) of 21 subjects were recorded in a choice reaction time task with a repeating eight-element long stimulus sequence. The regular event sequence was sometimes interrupted by 'perceptual' or by 'motor deviants' which both replaced an expected stimulus but either preserved or violated the sequence of motor responses. Response times confirmed that all subjects had acquired some knowledge of the sequential dependencies. By means of a post-experimental free recall and recognition test, subjects were classified as having either explicit or implicit knowledge of the event sequence. The ERPs showed different effects for different types of stimuli and the two groups. In the group of explicit learners, a larger N200 component was evoked by both types of deviants and a larger P300 by motor deviants only. In the group of implicit learners these 'perceptual components' remained unaffected. In contrast, in both groups of subjects the lateralized readiness potential (LRP) which accompanied motor deviants revealed a partial activation of the to be expected but incorrect response, i.e. motor learning. These results suggest that explicit learners acquire knowledge about both, stimulus and response dependencies while implicit learners acquire knowledge about response dependencies only.     

Reaction time and movement time as measures of stimulus evaluation and response processes

Reaction time has been divided into the time to initiate a response (RT) and the time to execute the motor response (MT) in many chronometric studies of intelligence. Our purpose was to determine which cognitive processes are reflected by RT and MT. To accomplish this, the latency of the P300 wave of the event-related potential was recorded concurrently with RT and MT measures in three experiments. P300 latency reflects the duration of stimulus evaluation relatively independently of response processes. In the first experiment, a Sternberg memory task was employed to manipulate stimulus classification requirements. In the second, the subjects' emphasis on either speed or accuracy of responding was examined during a task that also manipulated stimulus evaluation time. In the third experiment, a Stroop-like task was used to examine response processes. RT and P300 latency varied with manipulations of stimulus evaluation time, whereas MT varied with difficulty of motor execution. MT was also affected by stimulus classification processes. Both RT and MT were sensitive to processes involved in response bias and preparation. The possibility that the correlations of RT and MT with measures of intelligence are due to effects on a common stage of information processing cannot be rejected in the light of these results.     

The effect of explicitly varying the proportion of “same” and “different” responses on sex differences in the Shepard and Metzler mental rotation task

The mental rotation of three-dimensional objects is consistently identified as the most salient cognitive sex difference in humans. The Shepard and Metzler task (1971) requires participants to rotate an object in their “mind's eye” and then compare the shape to a second object to identify if the two objects can be aligned in an identical orientation (warranting a “same” response) or represent mirror image shapes of one another (warranting a “different” response). The mental rotation task not only involves a rotational component but also nonrotational components such as comparison and decision making. Recent research has suggested that the sex difference in mental rotation resides in the nonrotational aspects of “different” decisions specifically. This experiment examined this proposal by varying the proportion of “different” decisions across conditions. Participants were ether exposed to the traditional format (50:50 same/different) or a bias towards (75:25) or away from (25:75) different responses. Contrary to previous research, the sex difference was found to reside in “same” responses that required a greater degree of rotation when assessing error rates in mental rotation. Sex differences in mental rotation error rates were particularly sensitive to the rotational aspect of same responses, not rotational aspects of different responses nor nonrotational aspects of both same and different responses. For reaction time, however, a sex difference emerged in the nonrotational aspects of the task. The bias described here affected these nonrotational aspects of the task, but not the rotational aspects, in line with prediction. A second study reran the experiment without making the bias explicit. Under this implicit bias, no sex differences were identified between conditions.     

Influence of character strengths on mental health stigma

We examined traits of open-mindedness, kindness, hope, and social intelligence in the context of mental health stigma. Stigma – a process that objectifies and dehumanizes a person who has mental illness – diminishes people’s ability to control their behavior as coping with stigma requires self-regulation. Exploring mental health stigma through the lens of character strengths allows for understanding individual differences and kinds of characteristics that help decrease the ramifications associated with stigma of mental health. Several tasks explored the effects of character strengths on implicit and explicit mental health stigma: implicit association task, measures of willingness to interact with those with a mental health disorder, and a social distance task of self, friend, and person with a disorder. Character strengths of social intelligence and kindness were indicative of less stigma of mental health. More open-minded individuals tended to not hold individuals diagnosed with a mental health disorder personally responsible for acquiring that disorder.     

Response-repetition effects in task switching - dissociating effects of anatomical and spatial response discriminability

In task switching, response repetitions typically lead to performance benefits for task repetitions but costs for task switches. We examined whether this cost–benefit pattern is affected by response discriminability (RD), varying (a) the anatomical response separation (within-hand vs. between-hand responses) and (b) the spatial separation (close vs. far response keys). We assumed that anatomical RD increases response competition generally, whereas spatial RD increases the salience of left–right coding and thus facilitates response selection. In two experiments, we found that spatial RD increased the response-repetition costs in task switches but similarly decreased the response-repetition benefit in task repetitions. The effect of spatial RD was response-specific but did not interact with task switching. This data pattern is consistent with a recent account that proposed that facilitated response selection increases response “self-inhibition” after response execution. In contrast, the influence of anatomical RD primarily consisted of an overall increase of reaction-time level in all conditions, whereas error rates decreased, suggesting a general shift in response criterion. Taken together, the data suggest that a self-inhibition mechanism on the level of motor response codes contributes to response-repetition effects in task switching, which is possibly independent of task-specific mechanisms of strengthening of associations.     

Adaptation to visuomotor rotations in younger and older adults

Adaptation to a visuomotor rotation is known to be impaired at older adult age. The authors examined whether the impairment is present already at preretirement age and whether it depends on the difficulty of the adaptation task. Moreover, the authors tested predictions of the hypothesis that the age-related impairment pertains primarily to strategic corrections and the explicit knowledge on which they are based but not to the acquisition of an (implicit) internal model of the novel visuomotor transformation. The authors found an age-related impairment of adaptation and explicit knowledge already at preretirement age but no age-related change of aftereffects. With an incremental simplification of the adaptation task, age-related changes were able to be eliminated. Individual differences of the quality of explicit knowledge were associated with differences of adaptation, but not of aftereffects. When age groups were matched by explicit knowledge, age-related impairments of adaptation largely disappeared. However, a reliable difference remained in one of the experiments, suggesting that other processes of adjustment to a visuomotor rotation might be affected by aging as well.     

Maintaining readiness for mental rotation interferes with perceptual processes in children but with response selection in adults

Previous work revealed that mental rotation is not purely inserted into a same-different discrimination task. Instead, response time (RT) is slowed to upright stimuli in blocks containing rotated stimuli compared to RT to the same upright stimuli in pure upright blocks. This interference effect is a result of maintaining readiness for mental rotation. In two experiments we investigated previous evidence that these costs depend upon distinct sub-processes for children and for adults. In Experiment 1, the maintaining costs turned out to be independent of the visual quality of the stimulus for adults but not so for children. Experiment 2 revealed that the maintaining costs were greatly reduced for adults when they performed mental rotation as a go-no-go task, but not so for children. Taken together, both experiments provide evidence that whereas perceptual processes seem to be important for school-age children to maintain readiness for mental rotation, response selection is relevant for adults.     

Simple reaction time and predictive tracking in Parkinson's disease: do they converge on a single, fixed impairment of preparation?

Patients with Parkinson's disease exhibit a number. of abnormalities that seem more marked in circumstances in which stimulus and response are predictable in advance. In this article, we consider the prolonged movement onset latencies exhibited by Parkinsonian subjects in the tracking of predictable targets and in the simple reaction time (RT) task. It has been suggested that the performance impairments on both these tasks stem from a common planning deficit. We argue that the Parkinsonian tendency to refrain from predictive tracking cannot be ascribed to an inability to anticipate due to a planning deficit. The data are better accommodated by our alternative thesis that when Parkinsonians' response initiation lags behind that of normal subjects, this is a result of a strategic adaptation to an impairment of the accuracy of movements guided by an internal representation of the target. Our conclusion, that the primary impairment of predictive tracking is one of inaccurate movement execution rather than delayed response initiation, precludes postulation of the same deficit as a source of the selective prolongation of simple RT sometimes found in Parkinson's disease. Moreover, an analysis of the processing demands of the two tasks shows that the predictability that characterizes each of them is quite different in nature. Hence, the impairments in predictive tracking and simple RT tasks are unlikely to stem from a single mechanism that is defective in Parkinson's disease.     

注意力资源限制与双任务的相互干扰机制

采用心理不应期研究范式, 两个反应时实验检测了注意力资源分配的特征以及双任务的相互干扰机制。每次实验中, 要求被试快速、相继对高低音辨别任务(T1)和Stroop任务(T2)作出选择性反应, T1和T2间采用6种不同的时间间隔(SOA), 以系统考察不同SOA条件下两个任务的反应时走势。结果发现：(1) 在重叠的双任务情境中, T1的中枢加工导致在T2上出现显著的PRP效应, T2的中枢反应选择对T1的反应选择和反应执行加工同样产生显著的影响。SOA以及T2的难度与复杂度实质性地影响了T1的反应选择和反应执行加工。(2) 当两个任务同时需要进行中枢反应选择加工时, 一个任务占用更多的注意资源将导致另一任务获得较少的注意资源, 注意资源量的多寡直接决定了该任务的加工效率。(3) 两个任务的加工相互影响、相互制约, 这种制约机制不仅仅存在于中枢反应选择阶段, 在反应执行阶段仍然存在。     

The Self-Organization of Explicit Attitudes

ABSTRACT— How do minds produce explicit attitudes over several hundred milliseconds? Speeded evaluative measures have revealed implicit biases beyond cognitive control and subjective awareness, yet mental processing may culminate in an explicit attitude that feels personally endorsed and corroborates voluntary intentions. We argue that self-reported explicit attitudes derive from a continuous, temporally dynamic process, whereby multiple simultaneously conflicting sources of information self-organize into a meaningful mental representation. While our participants reported their explicit (like vs. dislike) attitudes toward White versus Black people by moving a cursor to a "like" or "dislike" response box, we recorded streaming x - and y -coordinates from their hand-movement trajectories. We found that participants' hand-movement paths exhibited greater curvature toward the "dislike" response when they reported positive explicit attitudes toward Black people than when they reported positive explicit attitudes toward White people. Moreover, these trajectories were characterized by movement disorder and competitive velocity profiles that were predicted under the assumption that the deliberate attitudes emerged from continuous interactions between multiple simultaneously conflicting constraints.     

A temporally sustained implicit theory of mind deficit in autism spectrum disorders

Eye movements during false-belief tasks can reveal an individual’s capacity to implicitly monitor others’ mental states (theory of mind – ToM). It has been suggested, based on the results of a single-trial-experiment, that this ability is impaired in those with a high-functioning autism spectrum disorder (ASD), despite neurotypical-like performance on explicit ToM measures. However, given there are known attention differences and visual hypersensitivities in ASD it is important to establish whether such impairments are evident over time. In addition, investigating implicit ToM using a repeated trial approach allows an assessment of whether learning processes can reduce the ASD impairment in this ability, as is the case with explicit ToM. Here we investigated the temporal profile of implicit ToM in individuals with ASD and a control group. Despite similar performance on explicit ToM measures, ASD-diagnosed individuals showed no evidence of implicit false-belief tracking even over a one-hour period and many trials, whereas control participants did. These findings demonstrate that the systems involved in implicit and explicit ToM are distinct and hint that impaired implicit false-belief tracking may play an important role in ASD. Further, they indicate that learning processes do not alleviate this impairment across the presentation of multiple trials.     

The time course effect of moderate intensity exercise on response execution and response inhibition

This research aimed to investigate the time course effect of a moderate steady-state exercise session on response execution and response inhibition using a stop-task paradigm. Ten participants performed a stop-signal task whilst cycling at a carefully controlled workload intensity (40% of maximal aerobic power), immediately following exercise and 30 min after exercise cessation. Results showed that moderate exercise enhances a subjects’ ability to execute responses under time pressure (shorter Go reaction time, RT without a change in accuracy) but also enhances a subjects’ ability to withhold ongoing motor responses (shorter stop-signal RT). The present outcomes reveal that the beneficial effect of exercise is neither limited to motor response tasks, nor to cognitive tasks performed during exercise. Beneficial effects of exercise remain present on both response execution and response inhibition performance for up to 52 min after exercise cessation.     

Novice motor performance: Better not to verbalize

Offline verbalization about a new motor experience is often assumed to positively influence subsequent performance. Here, we evaluated this presumed positive influence and whether it originates from declarative or from procedural knowledge using the explicit/implicit motor-learning paradigm. To this end, 80 nongolfers learned to perform a golf-putting task with high error rates (i.e., explicit motor learning), and thus relied on declarative knowledge, or low error rates (i.e., implicit motor learning), and thus relied on procedural knowledge. Afterward, they either put their memories of the previous motor experience into words or completed an irrelevant verbal task. Finally, they performed the putting task again. Verbalization did not improve novice motor performance: Putting was impaired, overall, and especially so for high-error learners. We conclude that declarative knowledge is altered by verbalization, whereas procedural knowledge is not.     

Motor Imagery Shapes Abstract Concepts

The concepts of “good” and “bad” are associated with right and left space. Individuals tend to associate good things with the side of their dominant hand, where they experience greater motor fluency, and bad things with their nondominant side. This mapping has been shown to be flexible: Changing the relative fluency of the hands, or even observing a change in someone else's motor fluency, results in a reversal of the conceptual mapping, such that good things become associated with the side of the nondominant hand. Yet, based on prior studies, it is unclear whether space–valence associations were determined by the experience of fluent versus disfluent actions, or by the mere expectation of fluency. Here, we tested the role of expected fluency by removing motor execution and perceptual feedback altogether. Participants were asked to imagine themselves performing a psychomotor task with one of their hands impaired, after which their implicit space–valence mapping was measured. After imagining that their right hand was impaired, right‐handed participants showed the “good is left” association typical of left‐handers. Motor imagery can change people's implicit associations between space and emotional valence. Although asymmetric motor experience may be necessary to establish body‐specific associations between space and valence initially, neither motoric nor perceptual experience is needed to change these associations subsequently. The mere expectation of fluent versus disfluenct actions can drive fluency‐based effects on people's implicit spatialization of “good” and “bad.” These results suggest a reconsideration of the mechanisms and boundary conditions of fluency effects.     

The effect of motor preparation on changes in h reflex amplitude during the response latency of a warned reaction time task

Monosynaptic Hoffman reflexes (H reflexes) were recorded from the soleus muscle during the response latency of a warned reaction time (RT) task that required plantarflexion of the foot. The task was done under four conditions of predictability of the response signal (RS), created by the factorial combination of foreperiod duration (1 and 4 s) and variability (fixed and variable). RT varied systematically with RS predictability and was facilitated in conditions that favored prediction of the RS. The response latency was divided into two successive phases by the onset of reflex augmentation: a premotor phase of constant reflex amplitude and a succeeding motor phase marked by progressively increasing reflex amplitude. Reflex augmentation during the motor phase was coupled more closely to the imminent movement than to the preceding signal to respond. The duration of the premotor phase was unaffected by RS predictability, but the duration of the motor phase (like RT) was shorter when the RS was more predictable. The maximum H reflex amplitude reached during the motor phase was greater when the RS was more predictable. The tonic level of H reflex amplitude during the premotor phase was greater in conditions that made prediction of the RS difficult. A second experiment showed that this difference was present throughout the foreperiod. These results suggest that conditions that favor prediction of the RS enhance motor preparation. changes in motor preparation (which affect RT) affect the processes underlying reflex amplitudes in the premotor phase and throughout the preceding foreperiod, in conditions that make prediction of the RS difficult, appear to reflect heightened general arousal.     

Preparatory Set,Response Complexity,and Reaction Latency

The interaction between preparatory set and response complexity was demonstrated in an experiment investigating the reaction latency of discrete arm movements. Following simple finger-lift reaction-time (RT) trials, subjects performed simple and complex versions of a discrete horizontal arm movement under one of two enforced preparatory set conditions. For the simple task, requiring subjects to attend to the components of the response prior to stimulus presentation (enforced motor set) produced significantly shorter RTs than when concentration was on the stimulus (enforced sensory set). However, RT differences for the complex version of the task failed significance. Theoretical implications of the results for Henry’s (1960) memory drum theory of neuromotor reaction were discussed.     

Stable implicit motor processes despite aerobic locomotor fatigue

Implicit processes almost certainly preceded explicit processes in our evolutionary history, so they are likely to be more resistant to disruption according to the principles of evolutionary biology [Reber, A. S. (1992). The cognitive unconscious: An evolutionary perspective. Consciousness and Cognition, 1, 93-133.]. Previous work (e.g., [Masters, R. S. W. (1992). Knowledge, (k)nerves and know-how: The role of explicit versus implicit knowledge in the breakdown of a complex motor skill under pressure. British Journal of Psychology, 83, 343-358.]) has shown that implicitly learned motor skills remain stable under psychological pressure and concurrent cognitive demands, and recently [Poolton, J. M., Masters, R. S. W., & Maxwell, J. P. (2007). Passing thoughts on the evolutionary stability of implicit motor behaviour: Performance retention under physiological fatigue. Consciousness and Cognition, 16(2), 456-468.] showed that they also remain stable under conditions of anaerobic fatigue that would have significantly challenged the survival skills of our ancestors. Here we examine the stability of an implicitly learned motor skill under fatigue conditions that primarily tax a different physiological system (the aerobic system), but which have equally strong evolutionary connotations. Participants acquired a throwing task by means of an errorless (implicit) learning method or an errorful (explicit) method. Motor performance in the errorless condition, but not the errorful condition, remained stable following an exhaustive VO2 max. running test. Our findings replicate and extend the work of Poolton et al., providing further support for Reber's evolutionary distinction between implicit and explicit processes.