Quick review of main points:
Rothbart, Davis-Stitt, & Hill (1997):
Arbitrary category boundaries and labels both
affect observers' judgments about the perceived
similarity of targets.
When people were within the same labeled
category, they were seen as more similar than
when they were in different categories, even
with the underlying "amount" of difference
between them was the same.
The presence of visual boundaries (heavy lines
marking off different sections of the scale) also
affected perceived similarity.
Results show the effects of BOTH within-category assimilation and between-category
accentuation (contrast effect).
No evidence of outgroup homogeneity was found.
Insko et al., 1994
In two mixed motive experiments comparing
the behavior of individuals and groups, Insko et
al. demonstrate that groups are more
competitive than individuals, and that this is
true whether comparing two groups with two
individuals, or comparing three groups with
The discontinuity effect was relatively constant
across six trials (Experiment 1).
Evidence of greater fear/mistrust and greed by
groups as compared to individuals suggests the
underlying causes of the discontinuity effect.
Groups were just as likely to make cooperative
agreements with one another as were
individuals, but they were less likely to honor