An Electrophysiological Study on Intra- and Inter-modal Duration Discrimination: Effects of Performance Level

An Electrophysiological Study on Intra- and Inter-modal Duration Discrimination: Effects of Performance Level Emi Hasuo (hasuo@ neurophy.med.kyushu-u.ac.jp) Faculty of Medical Sciences, Kyushu University/Japan Society for the Promotion of Science, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582 Japan Emilie Gontier (emilie.gontier.1@ulaval.ca) Laboratoire de Recherche en Psychologie de la Perception, Universite Laval, 2325 rue des Bibliotheques, Quebec, Quebec, G1V 0A6, Canada Takako Mitsudo (mitsudo@cog.inf.kyushu-u.ac.jp) Faculty of Information Science and Electrical Engineering, Kyushu University, 744, Motooka, Nishi-ku, Fukuoka, 819-0395 Yoshitaka Nakajima (nakajima@design.kyushu-u.ac.jp) Faculty of Design, Kyushu University, 4-9-1 Shiobaru, Minami-ku, Fukuoka, 815-8540, Japan Shozo Tobimatsu (tobi@neurophy.med.kyushu-u.ac.jp) Faculty of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582 Japan Simon Grondin (Simon.Grondin@psy.ulaval.ca) Laboratoire de Recherche en Psychologie de la Perception, Universite Laval, 2325 rue des Bibliotheques, Quebec, Quebec, G1V 0A6, Canada perception of time. However, there is no sensory organ specialized for perceiving time, and the brain needs to process and integrate the temporal information delivered from multiple sensory modalities. How the brain processes temporal information from different sensory inputs and whether or not there is a central clock mechanism for time perception has been one of the fundamental questions in time perception studies (e.g., Grondin, 2010; Mauk & Buonomano, 2004). When two brief signals are presented successively, they can mark an empty time interval in between. A time interval marked by signals of the same sensory modality is called an intra-modal interval whereas an interval marked by signals from different sensory modalities is called an “inter- modal” interval. Generally, sensitivity to time is better (which can be seen as lower discrimination threshold and/or less variability) for auditory than for visual signals (Grondin, 1993), and inter-modal intervals are much more difficult to discriminate than intra-modal intervals (Grondin & Rousseau, 1991). Gontier et al. (2013) investigated the brain activity related to such modality differences in duration discrimination using electroencephalography. Auditory (A) and visual (V) signals were used to mark the beginning and the end of the time intervals, and there were four modality conditions: AA, VV (intra-modal conditions), AV, and VA (inter-modal conditions). They recorded the event-related potentials (ERPs) while the participants categorized the presented time intervals as either ‘short’ or ‘long’; they should respond Abstract Duration discrimination is severely impaired when the duration markers are delivered from different sensory modalities (inter-modal) instead of from the same modality (intra-modal). The present study examined the brain activity related to this impairment using event- related potentials. Durations were marked either by two auditory signals (AA) or by an auditory and a visual signal (AV), and there were two levels of discrimination difficulty (easy and difficult). A negative component (contingent negative variation) which appeared between the two markers at fronto-central sites and is said to be related to time perception, was larger for AA than for AV, and was not influenced by discrimination difficulty. A principal component analysis showed that the first and the third principal component captured differences in brain activity patterns between sensory modalities and difficulties, whereas the second principal component could reflect brain activity related to time perception in general, regardless of the modalities. Keywords: Time perception; modality; event-related potentials; contingent negative variation; principal component analysis Introduction Many activities in our everyday life, for example, speaking, playing sports, and enjoying music, require precise