Effect of temporal and spatial expectations on auditory target detection

Reasonable inference and expectation of the auditory target is one of the key issues in speeding up the target detection.Using the reaction time task,the present study explored how temporal expectation and spatial expectation affect detection of the target tone.Expectations were created implicitly using a moving sound sequence,which moved with a regular or irregular pace,following a well-ordered or unpredictable spatial trajectory.There were four types of expectation:no expectation,only temporal expectation about the moment of target’s onset,only spatial expectation about the location of target’s occurrence,combined temporal and spatial expectation.The task for participants was to respond as quickly as possible to the target tone,which was usually presented following the sequence.We found（1） a significant independent effect of temporal expectation in speeding target discrimination and（2） benefits of spatial expectation which appeared only when targets occurred at the unpredictable moment.The above findings suggest that listeners choose temporal expectation in preference to spatial expectation during auditory target detection.Alternatively,they exploit spatial expectation when temporal information is uncertain or unavailable for prediction.