Distortion of visual and auditory duration in short term memory
Kohske Takahashi, Katsumi Watanabe
Poster
Time: 2009-07-01 09:00 AM – 10:30 AM
Last modified: 2009-06-04
Abstract
Many studies have investigated inter- and intra-modal processes of time perception by employing temporal two-alternative forced choice (tTAFC) paradigm. A tTAFC paradigm generally assumes no bias in time perception while the temporal property of interest is retained in short term memory. However, how temporal information is retained in short term memory is not well understood. We examined how duration information of visual and auditory event is retained in short term memory and found a systematic memory distortion for visual, but not auditory events.
In a trial, observers compared the duration of first stimulus with that of second stimulus. In Experiment 1, the stimuli were white circles on a gray background. The first stimulus was presented for 765, 882, 1000, or 1118 ms, and the second stimuli was presented for 235, 118, 59, or 0 ms longer or shorter than the first stimulus. The blank retention interval between the stimuli was varied between 0.5 to 5 s. From derived psychometric functions, we estimated point of subjective equity (PSE) and just noticeable difference (JND) for each interval condition. The retention interval did not change the JND, but significantly affected PSE: the first visual stimulus was perceived shorter than second one (about 50 – 70 ms) when the interval was longer than 3 s. No correlation was found between JND and PSE, suggesting that the effect was not due to decision bias in unconfident trials. In Experiment 2, the visual stimuli were substituted by auditory tones. No effect of retention interval on PSE was observed. In Experiment 3, the period of visual stimuli in Experiment 1 was replaced by a blank interval between visual flashes (85 ms). Results showed that there was no effect of retention interval on PSE for visual interval judgment, but JND increased (i.e., temporal resolution became lower) as the retention interval increased.
These results suggested that retention process for visual duration information may differ from that for auditory duration. In addition, the retention interval for visual memory had differential influences on duration and interval judgment, suggesting that the memory distortion may be a manifestation of specific process for visual duration retention.
In a trial, observers compared the duration of first stimulus with that of second stimulus. In Experiment 1, the stimuli were white circles on a gray background. The first stimulus was presented for 765, 882, 1000, or 1118 ms, and the second stimuli was presented for 235, 118, 59, or 0 ms longer or shorter than the first stimulus. The blank retention interval between the stimuli was varied between 0.5 to 5 s. From derived psychometric functions, we estimated point of subjective equity (PSE) and just noticeable difference (JND) for each interval condition. The retention interval did not change the JND, but significantly affected PSE: the first visual stimulus was perceived shorter than second one (about 50 – 70 ms) when the interval was longer than 3 s. No correlation was found between JND and PSE, suggesting that the effect was not due to decision bias in unconfident trials. In Experiment 2, the visual stimuli were substituted by auditory tones. No effect of retention interval on PSE was observed. In Experiment 3, the period of visual stimuli in Experiment 1 was replaced by a blank interval between visual flashes (85 ms). Results showed that there was no effect of retention interval on PSE for visual interval judgment, but JND increased (i.e., temporal resolution became lower) as the retention interval increased.
These results suggested that retention process for visual duration information may differ from that for auditory duration. In addition, the retention interval for visual memory had differential influences on duration and interval judgment, suggesting that the memory distortion may be a manifestation of specific process for visual duration retention.