What Happens in a Moment

Abstract

There has been evidence for the very brief, temporal quantization of perceptual experience at regular intervals below 100 ms for several decades. We briefly describe how earlier studies led to the concept of "psychological moment" of between 50 and 60 ms duration. According to historical theories, within the psychological moment all events would be processed as co-temporal. More recently, a link with physiological mechanisms has been proposed, according to which the 50-60 ms psychological moment would be defined by the upper limit required by neural mechanisms to synchronize and thereby represent a snapshot of current perceptual event structure. However, our own experimental developments also identify a more fine-scaled, serialized process structure within the psychological moment. Our data suggests that not all events are processed as co-temporal within the psychological moment and instead, some are processed successively. This evidence questions the analog relationship between synchronized process and simultaneous experience and opens debate on the ontology and function of "moments" in psychological experience.

Keywords: Simon effect; perceptual organization; psychological moment; serial processing; time.

Figure 1

Illustration of the paradigm used to check for the effect of subthreshold asynchrony. The curves represent the increase in luminance of the two target bars, A and B. The first increase in luminance is used as a prime and masked by the distracters (“priming” figure). The prime is asynchronous when the two bars increase their luminance asynchronously. The task of the participant is to decide whether the second increase in luminance is simultaneous or asynchronous (reproduced with the permission of Schizophrenia Bulletin).

Figure 2

Illustration of the paradigm used to measure a Simon effect when stimuli are asynchronous. The asynchrony is manipulated from 0 to 100 ms by 8 or 17 ms steps. The subjects decide whether the stimuli are simultaneous or asynchronous and press a response key accordingly. The Simon effect shows in a tendency to press on either the first or second stimulus side, whatever the side of this stimulus, as shown on the figure.

Figure 3

Illustration of one of the priming paradigms used to test how a 17 ms asynchrony is processed. Empty frames were used as primes, and were either simultaneous or asynchronous, with a 17 ms asynchrony. After a delay of 100 ms, one of the frame was filled in, representing the target, and subjects had to press on its side. The results showed that RTs were faster when the target was to the side of the 2d rather than the first frame.