able world in which it is easier to adapt - categorisation is a cognitive adaptation. For we do not have the capability to respond differently to each stimulus, whether it be a person, an object, or an event. Categorisation is important in every day life, as well as in the most extreme of circumstances - for example, the discrimination between friend and foe.For categorisation to be useful, we enhance the difference between groups. This was found to be the case at both social and physical levels, and later became known as the 'accentuation principle' (see above). However, the distinction between physical stimuli and 'social objects' must be made clear. We ourselves our 'social objects', thus, we are implicated by such categorisations. As Hogg and Abrams (1988) state: 'it would be perilous to disregard this consideration'. This can be seen in the accentuation of out-group homogeneity (Park and Rothbart, 1982).Tajfel (1981) made two hypothesis on the cognitive consequences of categorisation. First, that if stimuli are put into categories, then this in itself enhances the difference between groups. Secondly, on a social level, individuals of different groups appear more different from each other, and those of the same group, more similar. Tajfel studied judgements of physical stimuli, using two categories, and found that the extremes of these groups were exaggerated. However, the differences within the two categories were reduced. This was the first of many experiments testing the two hypotheses, all finding that introducing categorisation into an otherwise undifferentiated situation, distorts people's perceptual and cognitive reasoning, and their functioning. Further studies have been conducted with the aim of taking these findings beyond the physical level, and into the social context, by examining the favouritism of the in-group over the out-groups - pre judgement, or stereotyping.Horwitz and Rabbie (1982) reported on an earlier experim...
