Amplitude Scaling Compensates for Serial Delays in Correcting Eye and Arm Movements

Spatial and metrical parameters of the eye and arm movements made by human subjects (N = 7) in response to visual targets that were stepped unexpectedly either once (single step) or twice (double step) were studied. For the double-step, the displacement of a visual target was decreased or increased in amplitude at intervals before and during a movement. Provided the second target step occurred more than 100 ms before the onset of movement, the amplitude of the subjects' first response was altered in the direction of the new target location. But this amplitude scaling was not always sufficient to reach the new target location, and a second corrective response was required. The latency in producing this second response was greatly increased above reaction time latencies of movements to single-step targets, especially when the target change occurred 100 ms or more before movement onset. These findings suggest that even though serial processing limitations delay the production of a second corrective response, continuous parallel processing of visual information enables the amplitude of the first response to be altered with minimal delay. This enables some degree of real-time continuous control by the visuomotor control system.     

Sports participation at work: An aid to stress management?

This study examined the effects of sport participation on mood, including stress, arousal, and psychological reversals. The subjects (N = 42) of the study were enrolled in an international MBA program which included, in addition to a range of academic courses, a course in physical education for which attendance was voluntary. Subjects, 26 sport participants and 16 nonparticipants, completed mood measures on five occasions throughout a typical working day, including just before and just after a sport session. Significant differences on some mood measure items and a number of pre- to post-sport significant effects (seriousmindedness and stress) were found between the sport and non-sport group, as well as reversals in psychological state. These results suggest that sport may well act as a modulator of mood and/or an inducing agent for reversal and therefore may play an important role in stress management intervention programs at work.     

Naturalistic assessment of children's compliance to teachers' requests and consequences for compliance

Naturally occurring levels of teacher commands, child compliance to those commands, and positive and negative teacher feedback were studied in 19 teachers and 130 children in kindergarten through third grade. Seventy-five of the children had been identified as "making a good social adjustment" to school (high-rated) and 55 children were identified as "not making a good social adjustment" to school (low-rated). Results of intensive observation over a 4-wk period showed that: (a) individual teachers differed significantly in their overall use of commands; however, they did not differentially respond to high- versus low-rated children; (b) high-rated children were more likely to comply with commands than were low-rated children; (c) although the overall level of positive social consequences was extremely low, there was some indication that high-rated children were more likely to receive positive feedback for compliance than were low-rated children; (d) low-rated children received significantly more positive feedback than high-rated children for noncompliance; (e) teachers gave negative feedback for noncompliance at an equal level to both groups of children; and (f) although repeated teacher commands following noncompliance were equal across groups, low-rated children were exposed to significantly higher levels of repeated commands following compliance than were high-rated youngsters.     

Individual differences in cognitive strategy and personality traits as measured by the Sixteen Personality Factor Questionnaire

The relationship between personality and preference for use of the right or left hemisphere of the brain in cognitive processing was investigated. Lateral eye movements were recorded as 50 female and 20 male right-handed subjects considered questions requiring reflection. The questions were not obviously "verbal" or "spatial" in nature but did require differing levels of reflection. Questions requiring higher levels of reflection produced a higher rate of lateral eye movement responses. Percent right eye movement for individual subjects was then correlated with scores on the Sixteen Personality Factor Questionnaire, using both first-order factors and the second-order factor Cortertia, which has some face validity as describing the personality generally ascribed to those who produce mostly right lateral eye movements. No correlation was found between the preferred directions of eye movements and 16 PF factors, which suggests that the lateral eye movements reflect thinking and problem-solving strategies but are not associated with personality styles.     

Grouping of stimuli and apparent exceptions to the psychological refractory period

When a subject is called upon to respond independently to two stimuli, the second of the two responses is often delayed if the stimuli follow closely on one another, and this has led to the suggestion that in making decisions the human operator accepts and organizes the available input information intermittently in the manner of a discontinuous servo. According to this view two nearly simultaneous stimuli can only be dealt with equally fast if they are grouped into a single decision to respond to both stimuli; otherwise one will have to wait for the attention of the central mechanism until the other has been dealt with. In the present experiment it is shown that delays in the second response are not necessary or invariable, and that the pattern and timing of the second responses when they are performed without delay differ in important respects from those to be expected of grouped responses. It is concluded that the central mechanisms concerned in the response do not possess the limitations that the single channel theory would suggest.     

Movement refractoriness: The influence of response structure and speed

In the first experiment, refractoriness of a primary arm swing was studied using two movement speeds and three secondary responses (reversal, contralateral and ipsilateral thumb-lift). Pre-movement inter-stimulus intervals were 100, 200 or 300 msec and response-stimulus intervals ranged from zero to 200 msec. Accelerometers provided kinematic data. The second experiment repeated the reversal condition with the addition of EMG analysis.The prediction that the maximal speed condition would show a general intensification of control processes, and thus less refractoriness as compared to submaximal speed, was upheld for all response conditions. The findings also supported the prediction that the pattern of refractoriness depends on the functional relationships of the muscles concerned.The EMG analysis revealed that while the sequencing of muscle action was unchanged with movement speed, its phasing characterized the shifts in response metrics. The overall findings emphasize the need to view the refractoriness phenomenon in the context of anatomical and mechanical consequences of force changes in controlling limb movement as they interact with intentional command.