Scheduled for Research Consortium Measurement, Exercise Physiology and Motor Behavior Poster Session, Friday, April 28, 2006, 8:45 AM - 10:15 AM, Convention Center: Exhibit Hall Poster Area I


Increased Reaction Times in Nonspeeded Tasks: Effect of Delaying the Second Task

Lanie A. Dornier, Melanie A. Hart and T. Gilmour Reeve, Texas Tech University, Lubbock, TX

Research has shown that reaction times (RTs) to an initial task (finger lift) increase when participants are required to complete a second task (reach and grasp an object). The increase in RTs has been found for both speeded and non-speeded second tasks. In an attempt to understand the increased RTs for the non-speeded second task, various manipulations to the second task have been conducted (i.e., size/weight of target, distance/direction to the target, same hand vs. different hand grasps). The various manipulations have failed to alter the increased RT to the initial task. The present study was designed to determine if the effect of the non-speeded task on RTs is tied to a temporal association with planning the primary task. Specifically, RTs were examined for conditions in which initial task was followed by a short delay (2 seconds) or a long delay (4 seconds) before the initiation of the second task. It was hypothesized that with the longer delay there would be sufficient temporal separation between the initial and second tasks so that RTs to the initial task would not increase. Participants (N=22) completed four conditions. Each condition was presented in a block of 20 trials. The four conditions were randomized among the participants. All four conditions required the participants to perform a finger lift (initial task) as quickly as possible upon the presentation of an auditory stimulus. One condition (finger lift only) required the participants to perform only the initial task. A second condition (speeded second task) required the initial task to be followed as quickly as possible by a reach to grasp an object position approximately 12 inches from the participant's midline (second task). The other two conditions required a non-speeded second task. In one condition, the initial task was followed by a short (2 second) delay prior to execution of the second task, and in the other, the initial task was followed by a longer (4 second) delay prior to the second task. The repeated measures ANOVA indicated a significant effect for condition, F(3, 63) = 9.70, p < .05. Post-hoc analyses indicated RTs for the finger lift condition were significantly faster than the other three conditions. Both of the non-speeded conditions with short and longer delays resulted in increased RTs. Therefore, temporal separation of the initial and second tasks does not diminish the effect of non-speeded task on RTs.
Keyword(s): performance, research

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