Within-subject effects of number of trials in rat conditioning procedures.

D. A. Gottlieb (2008) reported finding no effects of number of conditioning trials in a series of between-subjects magazine approach experiments, when number of sessions and total training time were held constant. This article reports 7 comparable within-subject experiments that looked for effects of number of trials in a variety of conditioning preparations. Experiments 1-3 detected effects of multiplying the number of trials by factors of 4 and 8 in a conditioned magazine approach procedure in which visual and auditory stimuli were paired with food. Experiments 4A and 4B detected effects of a factor of 4 trials in a conditioned flavor preference procedure in which flavors were paired with polycose. Experiments 5 and 6 detected an effect of a factor of 3 trials in a conditioned taste aversion procedure and in a fear conditioning procedure, respectively. Results suggest that variables other than number of trials might play important roles in determining the acquisition of conditioned responding, but effects of number of trials can be detected with sensitive enough procedures.