Figure 6.

Results of the test session of Experiment 3. (Panel A) Responding to the light stimulus that was first introduced in the prior compound conditioning (overshadowing) phase. Lower levels of responding to the light indicate greater overshadowing by the cue that accompanied it in compound conditioning. CeA lesions interfered with the ability of the target of a feature-negative discrimination (Group TA) to overshadow conditioning to that light, but not with the ability of a consistently-reinforced stimulus to do so (Group TC). (Panel B) Responding to the auditory stimulus that accompanied the light stimulus during compound conditioning. In both panels, group designations indicate the nature of training to the auditory cue used in the overshadowing phase. CeA lesions interfered with the ability of a target of a feature-negative discrimination (Group TA) to acquire additional conditioned responding in that phase. TA and F refer to the target and feature from a feature negative discrimination, respectively, and TC and C refer to the consistently reinforced and nonreinforced stimuli (respectively) from a simple discrimination. The designations CeA and sham refer to rats with neurotoxic or sham lesions of the amygdala central nucleus (CeA), respectively.