Noise effects in learning experiments

Abstract

The effects of noise in learning experiments vary considerably, depending on the characteristics and duration of the noise, and the behavior through which learning is being measured. There can also be considerable individual differences in animals’ responses to noise, even between members of the same species. Acute, mild noise is typically no more than a distractor. As noise intensity increases, behavioral effects increase, ranging from increased rates of responding in lever-pressing experiments to freezing in radial-maze tasks. Some paradigms are relatively unaffected by noise, including purely appetitive tasks, such as solving mazes for food reward, and tasks such as the water maze, where the aversive properties of water immersion outweigh the aversive effects of noise. Individual differences in animals’ responsiveness to noise can predict learning performance, with stronger responses to noise being associated with more effective learning. Research using rats in our own laboratory shows that chronic exposure to mild but unpredictable noise can attenuate latent inhibition, the capacity to ignore a stimulus that has previously been conditioned to be irrelevant.