Response delays and the timing of discrete motor responses

A model for the timing of repetitive discrete motor responses is proposed, and a prediction of negative dependency between successive interresponse intervals is confirmed by data from a Morse key tapping task. A method that makes use of the first-order serial correlation between interresponse intervals is used to distinguish between variance due to a timekeeping process and variance in motor response delays subsequent to the timekeeper. These two quantities are examined as a function of mean interresponse interval.     

Some determinants of looking time under different instructional sets

Four groups of Ss were asked to look at sets of figures whose members differed in degree of complexity and asymmetry. Ss instructed to look as long as the figures were pleasing did so for a significantly shorter time than did Ss who were instructed to look as long as they cared to, as long as the figures were interesting, or until they could recognize the figures in a large group of similar figures. Results indicated that looking time was affected by both the complexity and the asymmetry/symmetry dimensions and led to the conclusion that looking time is primarily a measure of exploratory behavior.     

Inference of one's attitude from behavior recalled under linguistically manipulated cognitive sets

To test Bem's (1972) hypothesis that individuals infer their attitudes from information about their behavior in a given context, subjects were asked their attitudes about a course after reporting their behaviors for the course and receiving a linguistic manipulation intended to produce an intrinsic or extrinsic cognitive context (set). Intrinsic set was manipulated by having subjects complete statements of the form “I generally do X because I …”. Extrinsic set was manipulated by having subjects complete statements of the form “I generally do X in order to …”. A pretest found that the intrinsic form resulted in a class perceived as more interesting than useful while the extrinsic form resulted in a class perceived as more useful than interesting. The present experiment found that subjects' attitudes are derived from information about different behaviors under the two cognitive sets. The attitudes of extrinsic set subjects were correlated with behaviors relevant to obtaining course out-comes like grades (contingent behaviors) and uncorrelated with behaviors relevant to personal interest (noncontingent behaviors); the opposite was found for intrinsic set subjects.     

The configuration and relaxation of motor task sets

Often the performance of a task does not only require the processing of certain stimuli in certain ways, but also certain patterns of interlimb coordination. We studied shifts between different tasks involving different patterns of intermanual coupling by means of the timed-response procedure, which allows to trace state variables related to task sets. The tasks required the production of rapid bimanual reversal movements with symmetric or parallel directions. Symmetric movements are associated with symmetric coupling, as indicated by positive intermanual correlations between the directions of left-hand and right-hand movements, whereas parallel movements are associated with parallel coupling, as indicated by negative intermanual correlations. Task switches were associated with gradual changes of the intermanual correlations, which indicate the state of intermanual coupling as a major ingredient of a task set, in the course of action preparation. At short preparation intervals intermanual correlations were those appropriate for the preceding trial; with increasing preparation time they were replaced by those appropriate for the current trial, but the influence of the preceding trial did not disappear completely. In-between trials, intermanual coupling drifted toward a symmetric coupling, but not to uncoupled limbs. After a change of the task the specification of movement directions was slowed, but its initiation was not delayed. According to these results, task sets relax toward attractors which can be different from the absence of task sets. They are gradually configured during task preparation with a persistent influence of the preceding task, and the specification of response characteristics does not wait until the configuration of the new task set is completed. The research reported in this paper was supported by grant He 1187/14-1 of the Deutsche Forschungsgemeinschaft. We thank Barbara Herbst, Holger Küper, Kevin Schepers, and Elisei Rotaro for their support in running the experiment.     

Processing capacity under perceptual and cognitive load: a closer look at load theory

Variations in perceptual and cognitive demands (load) play a major role in determining the efficiency of selective attention. According to load theory (Lavie, Hirst, Fockert, & Viding, 2004) these factors (a) improve or hamper selectivity by altering the way resources (e.g., processing capacity) are allocated, and (b) tap resources rather than data limitations (Norman & Bobrow, 1975). Here we provide an extensive and rigorous set of tests of these assumptions. Predictions regarding changes in processing capacity are tested using the hazard function of the response time (RT) distribution (Townsend & Ashby, 1978; Wenger & Gibson, 2004). The assumption that load taps resource rather than data limitations is examined using measures of sensitivity and bias drawn from signal detection theory (Swets, 1964). All analyses were performed at two levels: the individual and the aggregate. Hypotheses regarding changes in processing capacity were confirmed at the level of the aggregate. Hypotheses regarding resource and data limitations were not completely supported at either level of analysis. And in all of the analyses, we observed substantial individual differences. In sum, the results suggest a need to expand the theoretical vocabulary of load theory, rather than a need to discard it.     

Relation of number of different responses to group size and stimulus words in a discrete free-association situation

FlekkØy, K., Holme, I. & Mohn, E. Relation of number of different responses to group size and stimulus words in a discrete free-association situation. Scand. J. Psychol., 1973, 14, 4–8.-An exploration of the total number (D) of different responses given to a stimulus word in a single-word, free-association situation showed that (1) the first 50 Kent-Rosanoff words (in Norwegian) were highly heterogeneous with regard to D; (2) was an asymptotic function of the number of subjects; and (3) the larger D for schizophrenics may be attributed to their higher frequency of individual responses. It was also indicated that D may not be a valid measure of the magnitude of the associative potential of the individual.     

Warm-up effects in the learning of discrete motor skills

Three experiments were conducted to determine the influence of warming-up activities on performance and on learning in two discrete motor tasks. During initial trials on the criterion task, Ss were given various types of warming-up activities having an activity-set that was either the same as or different from the criterion task. Test trials followed in which all groups practiced the criterion task only. No significant differences in performance on the criterion task were found regardless of the appropriateness of the warming-up activity during initial trials. The results suggested that warming-up properties are not a factor in original learning of discrete motor skills.     

The influence of cognitive set on performance and arousal under different noise loads

Three groups of 12 subjects each performed a mental arithmetic task while exposed to continuous white noise in two experimental sessions. In Session I, each group was exposed to a different noise level [56, 72.5, or 85dB(A)], whereas in Session II all had the medium [72.5 dB(A)] intensity. Arithmetic performance deteriorated with increasing noise intensity in Session I, and in Session II each group retained its position relative to the other two groups. Thus, the higher the noise intensity in the first session, the poorer the performance in the second session. These results suggest that the motivation and energy mobilized in Session II were determined by the cognitive set adopted to meet the demands of Session I. Arousal level, as measured by adrenaline excretion and heart rate, was higher during both experimental sessions than in a control session. The rise in adrenaline output was of the same magnitude regardless of the intensity of the noise, which indicates that the subjects adjusted to the increase in total load by slowing down their performance rather than by raising their energy mobilization. Heart rate rose in response to changes in noise level in Session II relative to Session I, regardless of the direction of the change.     

On the advance preparation of discrete finger responses

Most studies that examined the precuing of motor responses have been interpreted as indicating that response specification is a variable-order process. An apparent exception to this conclusion was obtained by Miller (1982) for the preparation of discrete finger responses. Precuing was beneficial only when the precued responses were on the same hand, suggesting that response specification occurs in a fixed order, with hand specified before other aspects of the response. Three experiments examined this discrepant finding for discrete finger responses. Experiment 1 demonstrated that with sufficient time (3 s), all combinations of responses can be equally well prepared. Experiments 2 and 3 showed that the precuing advantage for same-hand responses at shorter precuing intervals is due to strategic and decision factors, not to an ability to prepare these responses more efficiently. Preparation of finger responses, thus, also appears to be variable. This conclusion poses problems for Miller's extension of the precuing procedure to the evaluation of discrete versus continuous models of information processing.     

Physical Fitness as a moderator of cognitive work capacity and fatigue onset under sustained combat-like operations

A study was devised to investigate the role of physical fitness in moderating both cognitive work capacity and fatigue onset under sustained combat operations. Sixteen male ROTC cadets were followed through a 2.5-day, Pre Ranger Evaluation exercise. Prior to the start of the exercise, the cadets’ overall level of physical fitness was assessed by using five fitness indices (Harvard Step Test, chin-ups, push-ups, sit-ups, and two-mile run). Cognitive performance and subjective measures of fatigue state were assessed at regular intervals before, during, and 1 day after the exercise. The results suggest that fitness may attenuate decrements in cognitive work capacity for certain tasks requiring prolonged mental effort, particularly as the cumulative effects of sleep loss and other stressors begin to mount. Similarly, the results suggest that as overall stress levels increase, fitness may have a beneficial effect in moderating fatigue rate. Fitness did not significantly enhance the recovery process with respect to cognitive work capacity, and actually appeared to hinder recovery from fatigue.     

Strategic capacity sharing between two tasks: evidence from tasks with the same and with different task sets

The goal of the present study was to investigate the costs and benefits of different degrees of strategic parallel processing between two tasks. In a series of experiments with the dual-task flanker paradigm, participants were either instructed to process the tasks serially or in parallel, or—in a control condition—they received no specific instruction. Results showed that the participants were able to adjust the degree of parallel processing as instructed in a flexible manner. Parallel processing of the two tasks repeatedly led to large costs in performance and to high crosstalk effects compared to more serial processing. In spite of the costs, a moderate degree of parallel processing was preferred in the condition with no specific instruction. This pattern of results was observed if the same task set was used for the two tasks, but also if different ones were applied. Furthermore, a modified version of the central capacity sharing (CCS) model (Tombu and Jolicoeur in J Exp Psychol Hum Percept Perform 29:3–18, 2003) was proposed that accounts also for crosstalk effects in dual tasks. The modified CCS model was then evaluated by fitting it successfully to the present data.

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Repetition of a cognitive task promotes motor learning

Motor learning plays an important role in the acquisition of new motor skills. In this study, we investigated whether repetition of a cognitive task promoted motor learning. Fifty-one young adults were assigned to either the early, late, or control groups. All participants completed a mouse tracking task in which they manipulated a mouse to track a moving target on a screen. The cursor was rotated 165° in the counterclockwise direction from the actual mouse position, requiring participants to learn how to use a new tool. To determine the task performance, we calculated the distance between the cursor and target position. In addition, to assess the effects of a cognitive task on the progress of motor learning, curve fitting of the learning curves was performed for the total distance. Experiments were conducted as per the following schedule: learning day 1 (L1), learning day 2 (L2: the day after learning day 1), retention day 1 (R1: 2 weeks after learning day 1), and retention day 2 (R2: 4 weeks after learning day 1). Participants underwent mouse tracking for 20 min on L1 and L2 and for 3 min on R1 and R2. As a cognitive task, we adopted the N-back task. The early or late group performed the N-back task for 20 min before performing motor tracking task on L1 or L2, respectively. The control group did not perform the N-back task. Based on curve fitting analysis, it was observed that the rate of change for motor learning in the early group was higher than that in the control group. The retention of motor learning did not differ between all groups. Our results indicate that the repetition of a cognitive task enhanced in the early phase of motor learning of the mouse tracking task.     

Bio-inspired cognitive model of motor learning by imitation

Learning, and even more so by imitation, is an essential Cognitive Functions because it is carried out throughout life and allows us to adapt our behaviors from other beings through observation. In this work, we propose a model, and implementation of the cognitive function of imitation motor learning (IML), based on psychological and neuroscientific evidence. According to the evidence, learning by imitation includes imitation of action and imitation of action over an object sub-processes. The imitation of action consists of the movement of the limbs. The imitation of action over an object consists of the interaction with an object within the environment. We achieve an implementation of the proposed model for IML and endow a virtual entity with it. In order to validate the proposal, we use a case study to analyze the sub-processes performance. From results, we conclude that both imitation of action and imitation of action over an object sub-processes play an essential role in getting the agent to interact with stimuli within the environment.     

Component analysis with different sets of constraints on different dimensions

Many of the classical multivariate data analysis and multidimensional scaling techniques call for approximations by lower dimensional configurations. A model is proposed, in which different sets of linear constraints are imposed on different dimensions in component analysis and classical multidimensional scaling frameworks. A simple, efficient, and monotonically convergent algorithm is presented for fitting the model to the data by least squares. The basic algorithm is extended to cover across-dimension constraints imposed in addition to the dimensionwise constraints, and to the case of a symmetric data matrix. Examples are given to demonstrate the use of the method.The work reported in this paper has been supported by the Natural Sciences and Engineering Research Council of Canada, grant number A6394, and by the McGill-IBM Cooperative Grant, both granted to the first author. The research of H. A. L. Kiers has been made possible by a fellowship of the Royal Netherlands Academy of Arts and Sciences. We thank Michael Hunter for his helpful comments on earlier drafts of this paper.     

Information entropy analysis of discrete aiming movements

Information entropy and mutual information were investigated in discrete movement aiming tasks over a wide range of spatial (20-160 mm) and temporal (250-1250 ms) constraints. Information entropy was calculated using two distinct analyses: (1) with no assumption on the nature of the data distribution; and (2) assuming the data have a normal distribution. The two analyses showed different results in the estimate of entropy that also changed as a function of task goals, indicating that the movement trajectory data were not from a normal distribution. It was also found that the information entropy of the discrete aiming movements was lower than the task defined indices of difficulty (ID) that were selected for the congruence with Fitts' law. Mutual information between time points of the trajectory was strongly influenced by the average movement velocity and the acceleration/deceleration segments of the movement. The entropy analysis revealed structure to the variability of the movement trajectory and outcome that has been masked by the traditional distributional analyses of discrete aiming movements.