Jeffrey Zacks, a colleague here in Psychology, and his collaborators have been studying human perception of events for the last ten years. A recent paper, in press at the Journal of cognitive neuroscience, and available at his website (pdf) argues that perceptual event boundaries occur in experience at points where prediction becomes difficult.
[…] working memory representations of the current event guide perceptual predictions about the immediate future [less than 10 sec]. These predictions are checked against what happens next in the perceptual stream; most of the time perceptual predictions about what happens next are accurate. From time to time, however, activity becomes less predictable, causing a spike in prediction errors. These spikes in prediction error are fed back to update working memory and reorient the organism to salient new features in the environment. According to this model, the increase in prediction error and consequent updating results in the subjective experience of an event boundary in perceptual experience.
The tenets of Zacks’s view are (i) that the unity of experience consists in representations actively maintained in working memory; (ii) present experience consists partly in anticipations of future experiences. Memory, insofar as it enters the stream of experience, would be on this account proleptic, forward-looking; mere recall has no place.
Aristotle says that animals don’t recollect: they don’t search their memories for information about the past (De memoria ii, 453a8, Hist. anim. 488b26; see Grote, Aristotle 476). On what grounds he said that I don’t know, but whether it was a shrewd surmise or a lucky guess he seems to have been right. Aristotle also put forward a version of what became the predominant philosophical picture of memory—that it consists in the registering of an “impression” which is subsequently to be recalled, as if the mind had a filing-card drawer or a mental museum (such as figured in Ancient and Renaissance arts memoriæ). That picture, attractive though it is, may well be fundamentally misleading. Modelling biological memory on the specifically human capacity that consists in voluntary recall of items subject to intersubjective standards of accuracy (e.g., the procedures of memorization employed by the reciters of epic poetry, to take an example Aristotle would have known) may turn out to be yet another case where intuition has led us astray.
A predominantly proleptic function for working memory, moreover, fits nicely with theories according to which perception requires activity on the part of the perceiver, so that the perception of red, for example, to use Mohan’s example (taken from Justin Broackes) is effectively the perception of a pattern of sensations that arises from the perceiver’s having regarded the red thing from several perspectives—a feat normally posssible only by moving. Event perception too may be governed, if not by activity itself, then by anticipations of activity.