Fig. 1. A partial reinforcement (PR) schedule does not result in learning. Three
separate groups of snails were used. (A) A control group of snails
(N=15) received three continuous reinforcement 30 min training
sessions each separated by a 1 h interval. Learning occurred (ANOVA,
F14,2=32.07, P<0.001; session 3 significantly
less than session 1, P<0.01), and a long-term memory was formed
[the memory test session, 24 h after session 3, was not significantly
different from session 3 (P>0.05) but was significantly different
(P<0.01) from session 1]. Two other cohorts, each of 20 snails,
received three 30 min PR sessions each separated by a 1 h interval. One cohort
was administered a tactile stimulus on odd-numbered (B) pokes, while the other
was administered a tactile stimulus on even-numbered (C) pokes. In neither
group was there learning (i.e. there was no significant difference between
session 1 and sessions 2 and 3). Values are means + S.E.M.
