Assessing sensory capacity of animals using operant technology.

Operant technology is often employed in farm management (e.g., waterers in which an animal pushes a valve with its nose or snout [response] to receive water [reinforcement]). An animal learns when successive approximations to the desired response are reinforced, thereby establishing the operant behavior (shaping). Animals are challenged by schedules of reinforcement that increase level of operant response. The method has been used to obtain quantitative measures of preference for prepared feeds, flavors, and harvest methods and feed processing. Basic information on what an animal sees in terms of color, patterns, and illumination are cited. Innovative research on animals' ability to smell and to hear are reviewed. Studies on regulation of environmental conditions by the animals themselves through operant methods will contribute to needed knowledge about animal welfare. Several examples of these studies are included in this review. Results of numerous studies indicate that operant technology can be a powerful tool to assess the sensory capacity of animals.