Figure 1.

Apparatus used in object discrimination training (Experiment 1) and mnemonic similarity tests (Experiment 2). (A) L-shaped maze bounded by start area and choice platform. (B, C, D) Object pairs used in Experiment 1. (B) shows standard object pairs used for initial training, (C) shows the distinct LEGO® object pair that shared 60% volume and 38% visible features, (D) shows the similar LEGO® pair that shared 87% volume and 63% visible features. (E, F) Target and lure objects used in Experiment 2. (E) Shows the target (S+) object used throughout the mnemonic similarity pre-training and tests, paired with a distinct object that shared 65% volume and 38% visible features. Rats were trained to associate the target with a food reward before moving on to discrimination tests. (F) Shows the familiar target object paired with each of 4 lure objects in order of increasing similarity: a distinct lure object (‘Frog’), Lure 1 that shared 89% volume and 50% visible features with the target, Lure 2 with 92% shared volume and 71% shared visible features, and Lure 3 with 95% shared volume and 90% shared visible features.