Towards electrophysiological correlates of auditory perception of temporal order.

Recent studies have postulated that the temporal order (TO) of two successive events can be correctly identified if they are separated by an inter-stimulus interval (ISI) of at least 30 ms duration. Using Auditory Evoked Potentials, we tested 21 students for the cortical activation associated with TO detection of two successively presented tones in either 'easy' (ISI=60 ms) or 'difficult' (ISI=10 ms) conditions. The amplitude of P2 component was related to difficulty of TO perception and was significantly higher in 'difficult' than 'easy' condition. Moreover, in 'difficult' condition the correlation analyses revealed a negative association at both Fz and Cz electrodes between P2 amplitudes and the correctness level. Correct responses in this condition were accompanied by lower P2 amplitudes than the incorrect ones.

Auditory perception of temporal order in humans: the effect of age, gender, listener practice and stimulus presentation mode.

The temporal order (TO) of two auditory stimuli can be reported correctly when they are separated by a gap of approximate 30 ms. Since no clear evidence on individual differences in human sequencing abilities exists, we tested the effect of subjects' age and gender, as well as physical properties of presented stimuli and listener practice on the perception of TO. In two experiments, young and elderly listeners reported the TO of two clicks or tones. The TO threshold (i.e. the minimum temporal gap required to report the stimulus order at 75% correctness) was lower in young than elderly listeners, in men than women and for tones than clicks. Age-related deterioration depended on the physical properties of presented stimuli, remaining resistant to both gender and practice.