Abstract
Sensory information must be integrated over time to perceive, for example, motion and melodies. Here, to study temporal integration, we used the sequential metacontrast paradigm in which two expanding streams of lines are presented. When a line in one stream is offset observers perceive all other lines to be offset too, even though they are straight. When more lines are offset the offsets integrate mandatorily, i.e., observers cannot report the individual offsets. We show that mandatory integration lasts for up to 450 ms, depending on the observer. Importantly, integration occurs only when offsets are presented within a discrete window of time. Even stimuli that are in close spatio-temporal proximity do not integrate if they are in different windows. A window of integration starts with stimulus onset and integration in the next window has similar characteristics. We present a two-stage computational model based on discrete time windows that captures these effects.
Highlights
Sensory information must be integrated over time to perceive, for example, motion and melodies
If the central line is offset, i.e., the lower segment is offset either to the right or left compared to the upper segment, the offset is visible at the subsequent stream even though the flanking lines themselves are aligned (Fig. 1, vernier condition)
Our data suggests that integration is not determined by spatiotemporal proximity, but rather occurs only when offsets are presented within a discrete window of time
Summary
Sensory information must be integrated over time to perceive, for example, motion and melodies. If the central line is offset, i.e., the lower segment is offset either to the right or left compared to the upper segment (this is called a vernier), the offset is visible at the subsequent stream even though the flanking lines themselves are aligned (Fig. 1, vernier condition). In addition to the central line, a flanking line is offset with an offset in the opposite direction, the offsets integrate and cancel each other (Fig. 1, vernier–anti-vernier condition). Using the SQM, we show that spatio-temporal feature integration lasts up to 450 ms and is mandatory, i.e., observers are unable to report the offsets separately. Our data suggests that integration is not determined by spatiotemporal proximity, but rather occurs only when offsets are presented within a discrete window of time
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