Response strength as a function of stimulus novelty: Concept formation in the pigeon.

Cites a previous study which showed that a distinctive CS presented on the 1st trial of acquisition generated more responses after extinction than another CS presented regularly during acquisition. In the present study 140 pigeons were presented with a different distinctive CS on each 1st trial of 5 acquisition sessions. Ss were then broken down into 7 groups which were tested, following extinction, for residual response strength of (a) Day 1 novel CS, (b) Day 2 novel CS, (c) Day 3 novel CS, (d) Day 4 novel CS, (e) Day 5 novel CS, (f) the regular CS, and (g) a novel CS never presented before. Contrary to the previous study where a novel CS inhibited responding, Group 7 exhibited the most responding in this study. Results support a concept formation interpretation of the previous study and are difficult to explain from a "stimulus trace" or "identical elements" position. (PsycINFO Database Record (c) 2010 APA, all rights reserved)