Effects of stimulus probability on pupillary dilation and reaction time in categorization.
Stimuli presented with a low frequency elicit larger pupillary responses than those presented with a high frequency. Similar effects are known for motor responses observed in reaction time experiments. Utilizing this stimulus probability effect, we conducted a Go/NoGo reaction time experiment and measured pupillary dilation to evaluate categorization. We found no probability effect when participants used distinctive features to classify stimuli with different frequencies into the same category. If no distinctive features could be applied, however, the effect was observed in both pupillary and reaction time data. The stimulus probability effect can serve as a tool for the evaluation of categorization and is discussed in the context of orienting.
Reinhard
Günter
G
Faculty of Psychology, Philipps-Universität Marburg, Gutenbergstrasse 18, D-35032 Marburg, Germany. reinharg@staff.uni-marburg.de
Lachnit
Harald
H
König
Stephan
S
D000328:Adult; D001143:Arousal; D030141:Feedback, Psychological; D005260:Female; D006801:Humans; D007266:Inhibition, Psychological; D008297:Male; D010364:Pattern Recognition, Visual; D011337:Probability Learning; D011930:Reaction Time; D012025:Reflex, Pupillary; D012718:Set, Psychology