Scheduled for Motor Behavior and Measurement Posters, Wednesday, April 2, 2003, 1:00 PM - 2:00 PM, Convention Center: Exhibit Hall A


Divided Attention Costs for Speeded and Non-Speeded Secondary Tasks to Near and Far Targets

Lanie A. Dornier1, Melanie A. Hart2 and T. Gilmour Reeve1, (1)Texas Tech University, Lubbock, TX, (2)University of Northern Iowa, Ceder Falls, IA

Previously, Fischman, Kinley, and Lane (1999) found that reaction times (RTs) to a primary task were slowed when paired with a non-speeded secondary task. This finding was not replicated in a subsequent experiment (Dornier & Reeve, 2001). One difference between the experiments was the distance of the secondary target from the start key (approximately 6 in. and 20 in., respectively). Additionally, in neither experiment was movement time (MT) directly measured, thus it was not possible to verify movement differences. The purpose of the present experiment was to extend previous research in examining possible causes for the discrepancy in results. Subjects were asked to perform speeded and non-speeded movements to near (five inches from the start key) and far (15 inches from the start key) targets. Both RTs and MTs were measured. Twenty-four subjects participated in five conditions containing 20 trials each. The five conditions were (1) simple finger lift without the grasping movement, (2) speeded movement to a near target, (3) speeded movement to a far target, (4) non-speeded movement to a near target, and (5) non-speeded movement to far target. Order of conditions was counter-balanced across subjects. In the speeded conditions, subjects were told to lift their finger and grasp the object as quickly as possible. In the non-speeded conditions subjects were told to lift their finger as quickly as possible, wait two seconds before grasping the target object. RT data were analyzed in a one-way ANOVA across conditions. Results of RT data indicated a significant effect for Condition F (4, 92)=5.4, p< .01. The finger-lift condition was faster than all other conditions. MT data were analyzed in a 2 (speed) X 2 (target distance) repeated measures ANOVA. Results of the MT data indicated main effect for Speed, F (1, 23)=162.63, p<.01 and Distance, F (1, 23)=37.17, p<.01. MT was slower for the non-speeded condition as compared to the speeded condition, and MT was slower to the far target as compared to the near target. These results confirm the presence of the non-speeded task effect on RT, demonstrating the influence of a subsequent movement (speeded or non-speeded) on RT.

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