Chapter 6, on Perception and attention runs to about 50 pages and starts the second volume of the first book. This is the third of the part 2 exam chapters but TMA3 also uses the background theory provided here.
This chapter starts starts by considering how the bottom-up information coming from our senses (i.e. sensations) direct our attention and then follows on to look at how these are perceived as top-down information in our brain. Thus the pattern of light and dark remained the same yet our perception of it changed this into the cow that we perceived later when the additional cues were added. How we perceive a journey is both in general terms (semantic memory) and the instance of a particular journey (episodic memory) hence we may know what usually happens on the way to work yet may not recall the specific details of the journey today.
Attention is the process by which we allocate cognitive processing resources. We tend not to notice everything (e.g. the change in the person asking directions) and Kahneman (1973) suggests that we have a limited-capacity central processor i.e. that we have a limited capacity attention. However, there appear to be more specialised processing units around as Navon and Gopher (1979) found in their multiple-resources theory of attention. Whatever their number, Posner (1980) recognised that there is still a limited capacity and therefore our attention is directed in the manner of an attentional spotlight which acts to reduce the amount of processing undertaken (albeit this selective attention means that we ignore things outside the spotlight). This spotlight acts in the form of attentional tunnelling when there’s too much to consider and we are forced to ignore things or stimulus-induced shifts of attention (e.g. a loud bang). Broadbent (1954) suggested a bottleneck theory of attention that reduced the amount of information early on thus allowing for the limited processing power, the snag with this being that it doesn’t allow for contextual processing at higher levels of perception and in practice it appears that where the filtering is applied varies depending on the processing load. This all presupposes that everything is conscious i.e. that they are controlled processes but there are also automatic processes which avoid the issues around the limited processing capacity but at the expense of losing the detail. The Stroop test is one example of this and hence people find it difficult to read the colour when the word printed is at odds with the colour that it is printed in.
As with attention, there are a number of different theories of perception. The chapter first looks at Gregory’s (1966) constructivist theory of perception which considers that as we don’t use all of the sensory information to begin with, we are therefore assembling our perception from incomplete information and in doing so we construct hypotheses that are subsequently proven or disproven as more information arrives. This explains a number of optical illusions and the way that those in different cultures perceive these but it is not a complete explanation. Gibson’s (1950) idea of direct perception considers that everything is already there in the sensory information and that we perceive the world as a whole and moreover that we perceive it dynamically rather than as a series of static images (e.g. most visual illusions only work as static images); no hypotheses are required.
Phenomenological experience considers the whole area of perception to be a fusion of our prior experience, our current understanding and the context and tries to understand not only how we perceive things but what the experience of perception is like (e.g. a cube is a building block to a child but a dice to a gambler). Images are considered as consisting of a figure and ground (the background). Gestalt psychology considers the identification of whole objects and challenges the idea of an attentional spotlight.
In the real world there’s a lot of research in, for example, traffic collisions considering such things as the sensory conspicuity (will it flash out at you) and attention conspicuity (will you actually notice it).
For the exam, the key topics for this chapter are:
Bottleneck theories of attention
Limited capacity attention