Summary of the talk that Andrew Buskell (HPS) gave on 25th November, 2013
In philosophy, the view that our perceptual capacities are best explained in terms of the formal properties of sequential operations is probably best exemplified by Egan (2010). Such a view renders explanations of perception and perceptual capacities generic and disembodied – there is no attempt to involve either the body of a perceiving organism, nor the content of such perceptions in anything other than a heuristic ‘gloss’ of what an individual might be doing or perceiving in a particular context.
I contrast to this position, I attempted to articulate and defend a position taken in the history of psychology, namely the direct perception of invariances, proposed and elaborated by the so-called ecological psychologists – predominantly J.J. Gibson and his students. The ecological psychologists argued that (at least) we directly perceived changing patterned stimulation, and that invariants allowed us to ‘hone in’ on what was salient in our environment. For example, we might think that the invariant Eiffel Tower allows us to locate ourselves and navigate through the ever-changing streets of Paris. While such a strategy does not obviate the need for the detailed computational explanations that Egan proffers, it does point towards the fact that there are important features in perceptual content – suggesting that her sparse, content-less account might not be satisfactorily explanatory.
I tried to motivate my account by pointing towards what I take to be an exemplary model of such direct perception: the echolocation of bats in the genus Rhinolophidae. These bats emit a characteristic echolocation call when hunting. Interestingly, in comparison to other bat echolocation calls, the narrow frequency band of Rhinolophidae (around 80 kHz) has to be supplemented by embodied strategies in order to extract salient information about the external world. In particular, these bats vigorously wiggle their ears in order to extract amplitude variations to determine the relative elevation of prey. However, the most interesting aspect of these bats’ hunting habits lay in how this echolocation call leads to the direct perception of prey: their narrow frequency-band call reflects off the wing-beats of prey, causing Doppler-shifted ‘pings’ in the echo.
At the end, I suggested that these bats are a counter-example to Egan’s account: not only does such an account necessarily involve bodily strategies (‘ear-wiggling’ among others not mentioned here), but is explanatory only when we give recourse to the perceptual content (the Doppler-shifted ‘pings’). Though computational descriptions are without a doubt helpful and part of the explanatory story, it seems as though a full and convincing account of perception – at least in the case of Rhinolophidae – will have to implicate other structures.
Egan, F. (2010) ‘Computational models: a modest role for content’, Studies in History and Philosophy of Science, Vol. 41, pp. 253 – 259.