TEMPORAL CHARACTERISTICS OF THE SURPRISE REACTION INDUCED BY SCHEMA-DISCREPANT VISUAL AND AUDITORY EVENTS

Two experiments investigated the effects of a schema-discrepant event on the surprise reaction. Schema-discrepancy concerned a physical feat ure of irrelevant distractor words that were presented while the subje cts performed a choice reaction time task. The stimulus onset asynchro ny (SOA) between the distractors and the task-relevant stimuli was man ipulated in both experiments. The occurrence of the schema-discrepant event led to subjective feelings of surprise and enhanced recall of th e stimulus material. In Experiment 1, the presentation of a schema-dis crepant auditory event resulted in a pronounced increase of reaction t ime (RT) with a 0.2sec SOA but not with a 1.5sec SOA. In Experiment 2, the effects of both fixed and variable SOAs of four different lengths (simultaneous onset, 0.5sec, 1sec, or 2sec SOA) were investigated wit hin a visual task context. The increase of RT was found to be most pro nounced with SOAs of 0.5sec and 1sec respectively, and more pronounced with variable than with fixed SOAs, especially with a simultaneous on set. These results provide information about the temporal characterist ics of the inhibitory component of the surprise reaction, and suggest that the inhibitory effects of surprise depend considerably on the sub jects' state of preparation for the experimental task.