Effects of distraction and task complexity on reaction time in obese persons

40 obese and 40 normal weight individuals were given a series of reaction time (RT) tasks in the presence or absence of a distracting 75-dB static noise under varying levels of task complexity. Both RT and movement time (MT) from a "home" button to a response button were recorded. There were no significant differences in RT between obese and normal subjects although a significant interaction between task complexity and subjects' weight showed that obese subjects had a faster mean RT on the 1-light task but slower RTs on the choice-discrimination tasks with 2, 4, or 8 lights. Obese subjects had a significantly faster mean MT at all levels of task complexity. The distracting stimulus had no differential effect on over-all RTs although an interaction of distraction X task complexity was obtained. The distractor significantly decreased MT for all subjects with no differential for the groups. The results are not in accordance with previous RT studies which supported the internality/externality hypothesis about obesity but rather support the view that obese subjects approach the experimental task with a differential level of motivation or response set.