Group position as a function of member attitudes. Choice shift effects from the perspective of social decision scheme theory.

500 undergraduates made decisions as individuals or 4-person groups about several attitude objects along a 7-point semantic differential scale and about several social issues along a percentage scale. Individual-group mean differences (both within and between Ss) suggested that choice shift effects observed in other studies also characterized these data, but inspection of entire distributions suggested that conclusions based on means alone (or other single statistics) may be incomplete. The nature of individual-group distributional differences aided the interpretation of choice shift effects. Predictions from several common social decision scheme models were compared with the group attitudinal decision distributions to ascertain the general kind of social process theory that might be required. A majority-averaging decision scheme best predicted the semantic differential items but not percentage items. A model incorporating Ss' perceptions of the population preferences also gave a generally accurate account of group attitudes for the semantic differential items.