PubMed Health⌕ Search

PubMed · 11548035

A more complete task-set reconfiguration in random than in predictable task switch.

Abstract

Three experiments are presented that compare the cost found when switching from one task to another in two different conditions. In one of them, the tasks switch in predictable sequences. In the other condition, the tasks alternate at random. A smaller time cost is found in the random-switch condition when enough preparation time is allowed. Such an effect is due to the random-switch cost continuing to decrease with preparation time after the predictable-switch cost has reached an asymptote. Although the relationship between number of repetitions of one task and time cost is different in the random- and the predictable-switch conditions, only the latter shows the presence of an "exogenous" component of cost. The implications of this finding are discussed in relationship with the usual distinction between an endogenous component of switch cost that is affected by preparation time and another exogenous, residual component (e.g., Rogers & Monsell, 1995). It is proposed that a different kind of task-set preparation is at work when tasks alternate at random.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

F J Tornay, E G Milán. 2001. A more complete task-set reconfiguration in random than in predictable task switch.. https://doi.org/10.1080/713755984

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

Dynamics of hand preference in 4 year-old children.

Hand preference in groups of 4 year-old children towards either end of the skill continuum (as determined by the Movement ABC test) was explored by means of a catching task in which the 'direction of approach of the ball' was used as a control parameter within a dynamical systems framework. In Condition 1, the ball direction was systematically scaled in degrees from the right side of the subject to the left and vice versa. In Condition 2, the spatial location of the ball direction was varied randomly, rather than systematically, over the same range as for Condition 1. In both conditions, the two groups of children were shown to switch between hands (from left to right and vice versa) at well-defined positions on the scale. The different scale values obtained when ball direction was scaled from left to right compared with right to left were used to define hysteresis areas. These areas were more extensive and located more to the left of the midline for the group towards the less skilled end of the continuum than for those towards the more skilled end. Additionally, the less-skilled children were shown to use the right hand more to catch the balls delivered to the left side than did the more skilled children. In Condition 3, objects were placed on the table of the ball-delivery apparatus in order to make the catching action more complicated. The less skilled group were shown to use the right hand more than the left hand in all catching positions whereas the more skilled group showed an equal usage of both catching regimes.

Attention↗

Saccadic inhibition in voluntary and reflexive saccades.

The present study investigated saccadic inhibition in both voluntary and stimulus-elicited saccades. Two experiments examined saccadic inhibition caused by an irrelevant flash occurring subsequent to target onset. In each trial, participants were required to perform a single saccade following the presentation of a black target on a gray background, 4 degrees to the left or to the right of screen center. In some trials (flash trials), after a variable delay, a 33-msec flash was displayed at the top and bottom third of the monitor (these regions turned white). In all experimental conditions, histograms of flash-to-saccade latencies documented a decrease in saccadic frequency, forming a dip, time-locked to the flash and occurring as early as 60-70 msec following its onset. The fast latency of this effect strongly suggests a low-level, reflex-like, oculomotor effect, which was referred to as saccadic inhibition. A novel procedure was developed to allow comparisons of saccadic inhibition even across conditions, which in the absence of a flash (no-flash trials) produce dissimilar saccadic reaction times (SRTs) distributions. Experiment 1 examined the effects of the fixation stimulus on saccadic inhibition by contrasting three conditions: a gap condition (fixation stimulus disappeared 200 msec prior to target onset), a step condition (offset of the fixation stimulus was simultaneous with target onset), and an overlap condition (the fixation stimulus remained on for the duration of the trial). The overlap condition produced substantially stronger saccadic inhibition, relative to the gap and the step conditions. Experiment 2 contrasted the saccadic inhibition effect obtained for prosaccades (saccades aimed at the target) with the effect obtained for antisaccades (i.e., saccades aimed away from the same target). The onset of saccadic inhibition was earlier, and its magnitude was stronger, for antisaccades, relative to prosaccades. The plausibility that the superior colliculus is the neurophysiological locus of the saccadic inhibition effect was explored.

Attention↗