Abstract

This paper first advances and discusses the hypothesis that so-called “iconic” or (for the auditory sphere) “echoic” memory is actually a form of perception of the past. Such perception is made possible by parallel inputs with differential delays which feed independently into the sensorium. This hypothesis goes well together with a set of related psychological and phenomenological facts, as for example: Sperling’s results about the visual sensory buffer, the facts that we seem to see movement and hear temporal Gestalts, and the fact that we sometimes seem to hear sounds only after they have stopped. In it most simple form, and formulated in the somewhat misleading information processing idiom, my hypothesis says that each one of a number of parallel input lines with different delays feeds into a spatially separate sensory unit. The set of such units then holds information about the immediate past in what one might call a “chronotopic” sensory map. This contrasts with the idea (common in sensory buffer theory) that the received sensory information is kept (while possibly decaying) in the same unit for some time after it occurred. The hypothesis also contradicts the theory that all sensory information passes through the same unit but is then successively passed through a unidirectional chain of separate units, where the past experiences then become represented (the shift register hypothesis). The main advantage of my theory, beside the natural explanations it offers for the above-mentioned kind of phenomena, is that it postulates a parallel – and therefore robust – rather than a serial mechanism for the registering of temporal information. It can of course easily be modified to fit more complex models of the sensory cerebral code(s) as well as of the chronotopic representation as such. In the second part of my poster, I advance a corresponding hypothesis for those motor commands which control brief movements. At closer inspection, most socalled “ballistic” movements do not seem to be truly ballistic (in the sense in which the movement of a cannonball is so) since the brain must exert some kind of feedforward control over the later part of their trajectory. I suggest that this control is at least sometimes realized by means of differentially delayed output from a chronotopic representation of successive segments of the movement. Not only could this be a biologically natural way of ensuring efficient adaptability of the movement; the hypothesis also explains the not uncommon experience of “seeing the whole movement laid out in advance” when it is initiated.