What does preferential viewing tell us about the neurobiology of recognition memory?

The two most common paradigms for testing recognition memory in nonhuman primates provide conflicting evidence about its underlying neurobiology. The most widely used paradigm, preferential viewing, likely confounds memory with nonmnemonic processes like novelty processing, habituation, motivation, and others. Despite widespread use, preferential viewing correlates poorly with more traditional measures of explicit recognition. We propose that memory paradigms that require explicit choices should be preferred by researchers and weighted more heavily by readers. The two tests most widely used in nonhuman primates to assess the neurobiology of recognition memory produce conflicting results. Preferential viewing tests (e.g., visual paired comparison) produce robust impairments following hippocampal lesions, whereas matching tests (e.g., delayed nonmatching-to-sample) often show complete sparing. Here, we review the data, the proposed explanations for this discrepancy, and then critically evaluate those explanations. The most likely explanation is that preferential viewing tests are not a process-pure assessment of recognition memory, but also test elements of novelty-seeking, habituation, and motivation. These confounds likely explain the conflicting results. Thus, we propose that memory researchers should prefer explicit matching tests and readers interested in the neural substrates of recognition memory should give explicit matching tests greater interpretive weight. [ABSTRACT FROM AUTHOR]