The classification of social stimuli: “Social” and “non-social” distraction in the albino rat

Abstract

Rats were trained on a vertical vs. horizontal stripe discrimination with hunger drive and food reward. After a very stable level of performance was reached, both stimulus doors were unlocked and various distracting stimuli were introduced in the vicinity of the previously incorrect doorway. Three distracting stimuli were used: ( a) a stationery white cardboard rat, ( b) a small toy dog moving through the incorrect doorway, and ( c) a live rat moving through the incorrect doorway. All three distracting stimuli increased errors. The distracting effects were monotonically related to the complexity of the distracting stimuli, increasing in effectiveness from the cardboard rat, to the toy dog, to the live rat. The results are interpreted in terms of the increasing complexity of the distracting stimuli. Two dimensions making up this gradient of complexity are suggested; the amount of stimulus movement and thè number of activated sense modalities. Krech & Crutchfield's suggestions that a continuum of social stimulation should vary in mobility, capriciousness, and unpredictability are also applied in discussing the results.