The homunculus argument is a fallacy . Little man. Light from the outside world forms an image on the retinas in the eyes and something in the brain looks at these images as if they are images on a movie screen. David Marr. Nature of this internal viewer. The assumption here is that there is a ‘little man’ or ‘homunculus’ inside the brain ‘looking at’ the movie. The reason why this is a fallacy – ask how the homunculus ‘sees’ the internal movie. Another homunculus inside the first homunculus’s ‘head’ or ‘brain’ looking at this ‘movie’ – infinite regress.
The problem with the homunculus argument is that it tries to account for a phenomenon in terms of the very phenomenon that it is supposed to explain. Hippocrates cut the eye of a bull. Upside down image. Vision in action Our vision system is not there to faithfully record the image outside, it is there to give us the necessary information for us to behave appropriately. Not a camera. There for us to make sense of what is out there, how to interact with it, and to actively seek information.
Eyes flick from place to place, 3-5 times a second in constant motion – Yarbus 1967. Central part of the vision gives the most detail therefore eyes fall on interesting parts of the picture that will give the most information. Eyes. Acuity decreases with eccentricity (sharpness; a measure of the extent of deviation from circularity. Away from the centre becomes more blurred. ) . Vision loses the ability to see fine detail away from the centre of vision. Active process of grabbing information, use information to guide movements to the next point of interest.
Eye movements highly structured. (picture of where we look on girl) Damage to the system Kenneth Craik – the Nature of Explanation (1943) “In any well made machine one is ignorant of the working of most of the parts – the better they work the less we are conscious of them …….. It is only a fault which draws our attention to the existence of a mechanism at all. ” For example visual neglect – only see half the world. Continually pulled to the right, ignore things on the left.
From this can determine that in the brain there must be something that normally allows objects to grab attention and then be processed thoroughly. Damage allows us to see what has been damaged, what the job of this area is, gives insights. Do you see what I see? Isihara plates- some can see, some cannot – depends on the physiology – depends on type of colour vision. Wouldnt be able to see at night scotopic vision. Greeness an invention of the brain. Why do we see things that others may not be able to see? Adaption, ripe fruit?
Conscious vision, visual processing without consciousness (avoiding chair in room), light into electrical signals. Vision takes place within the brain. Processes – Lecture focus Light (luminance, wavelength) > Neural encoding (retina, cortex etc …) Representation (patterns, colour, depth) > Behaviour (aims, actions, emotions) > ?? Approaches to vision Psychophysical (physical events to perceptual events) Neurophysiological (actions of single cells, groups of cells, etc. ) Neuropsychological (brain damage, brain imaging) Computational (models, computer simulations).