Assessing the Value of Television as Environmental Enrichment for Individually Housed Rhesus Monkeys: A Behavioral Economic Approach.

The goal of this study was to evaluate television as a source of environmental enrichment for individually housed rhesus monkeys (Macaca mulatta) by using the concepts of behavioral economics. Phase I entailed the use of operant conditioning to assess the behavior of eight rhesus monkeys given the opportunity to control their environment through lever activation of a television (TV). Success in shaping was variable, and only two animals successfully acquired lever pressing. Phase II used an alternating reinforcement/ extinction procedure as a control method to determine the degree to which lever pressing depended on TV presentation. Both animals responded with more lever pressing on the days when lever pressing produced TV. The first animal, tested with the alternating reinforcement/extinction procedure for 12 weeks yielded a mean significant difference of 3.85 (p = 0.036); the second assessed for 9 weeks was associated with a mean significant difference of 6.0 (p = 0.018). Therefore, TV (and not lever pressing itself) was positively reinforcing. The final phase of the study progressively increased the fixed ratio (FR) from 1 to 8. Linear regression of the data points, plotted as the log of price (or FR) vs the consumption of TV, revealed a significantly negative slope (-2.179, p, 0.05) and accounted for 89% of the variance. The negative demand curve suggested that TV is not a valued commodity and is highly elastic. TV provided to individually housed rhesus monkeys appears to be a weakly positive reinforcer for some animals, which may contribute to overall environmental enrichment.