Academic journal article Perception and Psychophysics

Visual Onset Expands Subjective Time

Academic journal article Perception and Psychophysics

Visual Onset Expands Subjective Time

Article excerpt

We report a distortion of subjective time perception in which the duration of a first interval is perceived to be longer than the succeeding interval of the same duration. The amount of time expansion depends on the onset type defining the first interval. When a stimulus appears abruptly, its duration is perceived to be longer than when it appears following a stationary array. The difference in the processing time for the stimulus onset and motion onset, measured as reaction times, agrees with the difference in time expansion. Our results suggest that initial transient responses for a visual onset serve as a temporal marker for time estimation, and a systematic change in the processing time for onsets affects perceived time.

(ProQuest Information and Learning: ... denotes formulae omitted.)

Our estimation of time does not always correspond to physical reality, but is subject to distortion, depending on the temporal configuration of the stimulus (Arao, Suetomi, & Nakajima, 2000; Nakajima, ten Hoopen, Hilkhuysen, & Sasaki, 1992; Nakajima et al., 2004; Nakajima, ten Hoopen, & van der WiIk, 1991; Rose & Summers, 1995) or the observer's internal state, such as the state of attention (Brown, 1985, 1997; Coull, Vidai, Nazarian, & Macar, 2004; DeWolfe & Duncan, 1959; Tse, Intriligator, Rivest, & Cavanagh, 2004; Zakay, 1993). Moreover, our voluntary action is also known to distort perceived time (Yarrow, Haggard, Heal, Brown, & Rothwell, 2001; but see Alexander, Thilo, Cowey, & Walsh, 2005).

One of the most influential models of time perception is the scalar expectancy theory, or SET (Gibbon, 1977; Gibbon, Church, & Meek, 1984). The SET model consists of several functional components. The first component is a clock process-a pacemaker generating pulses (Creelman, 1962; Treisman, 1963). The pulses are gated by a switch, which is controlled by time markers indicating the beginning and the end of an interval to be estimated. While the switch is open, the pulses accumulate in working memory, representing the online estimation of the duration. After the switch closes, the accumulated pulses, which correspond to the total duration estimated, are transferred to a more long-lasting reference memory, available for later comparison. The comparison process evaluates the duration previously stored in reference memory and the online estimate of a duration accumulated in working memory. The result of this comparison is used for making relative time judgments.

This model suggests that there are several factors that can lead to a distortion of time perception. First, the opening and closing of the switch gating the pulses might involve some processing delays. When the duration of an event is estimated, the beginning and end of the event need to be marked. If the opening of the switch were delayed, the estimated duration would become shorter. Similarly, if the closing of the switch were delayed in comparison with the opening, the estimated duration would be lengthened further. Systematic manipulations of the delays would result in a time distortion (see, e.g.. Yarrow, Haggard, & Rothwell, 2004). second, the rate of the pulses is not necessarily constant. Although SET does not specify what constitutes the pulse generation, both attention and the number of changes experienced by observers seem to play an important role here. For example, it has been suggested that attention and arousal increase the speed of the internal clock. This account has been applied to the past findings that when a person directs his or her attention to temporal events, the perceived duration becomes longer (Brown, 1985, 1997;Coulletal.,2004;DeWolfe&Duncan, 1959). It has been proposed that changes in a stimulus lengthen perceived duration (Block, 1982; Gibson, 1975; Poynter, 1989). For example, intervals containing many events or movements (i.e., changes in position) are perceived to be longer than those involving fewer events (Brown, 1995; Kanai, Paffen, Hogendoorn, & Verstraten, 2006). …

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