Scaling Pigeons' Choice of Feeds: Bigger Is Better

Abstract

Preferences of hungry pigeons among 10 grains and pellets were analyzed using a Thurstone scaling procedure. The recovered scales were positively correlated with size of the feed. The correlations improved when the Thurstonian assumption of equal-sized discriminal dispersions (Case V) was replaced with the assumption of proportional-sized dispersions (Case VI), as entailed by Weber's law. The correlations weakened when the experiments were conducted with the pigeons close to their freefeeding weights, where the probability of sampling alternative grains increased. In the final experiment, exposure to a large pellet shifted the preferences between two smaller pellets.Key words: reinforcers, grain, preference, Weber's law, Thurstone, Fechner, scaling, magnitude of reinforcement, quality of reinforcement, foraging, food choice, pigeons Discriminating nuances in the quality of reinforcers is a major preoccupation of humans. Everything is rated, critics outnumber creators, and books-of-lists top the lists of best selling books. For luxury items such as wines and stereos, marginal utility seems never to decrease, with large premiums paid for differences in quality that require years of training to discriminate.Despite the importance of quality in human economy, little attention has been paid to it in the learning literature. Many texts merely refer to Elliot's (1928) classic study in which it was found that rats perform better for wet bran than for sunflower seeds, or to Young's (1928) demonstration of rats' preferential discrimination among types of grain. Thereafter, discussion of quality is usually embedded in that of quantity. Many of the extant studies of quality of reinforcers employ sucrose, whose concentration can be conveniently varied over a large range (Young, 1961

Comparison of the effects of clozapine and 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) on progressive ratio schedule performance: evidence against the involvement of 5-HT1A receptors in the behavioural effects of clozapine

“…This parameter is believed to provide a quantitative measure of the efficacy or value of positive reinforcers (Killeen 1994;Bizo and Killeen 1997;Killeen and Sitomer 2003;Reilly 2003). The empirical basis for this interpretation of a derives from the effects of manipulations of the 'hedonic quality' (assessed by reinforcer selection in choice paradigms; Killeen et al 1993) and magnitude of food reinforcers; such manipulations were found to produce reliable and selective effects on a (Bizo and Killeen 1997;Killeen and Sitomer 2003;Reilly 2003). Thus the present results and the earlier observations cited above are consistent with the notion that both clozapine and 8-OH-DPAT enhance the value of food reinforcers.…”

Rats don’t always respond faster for more food: The paradoxical incentive effect

“…Pigeons can discriminate small differences in sizes of grain and strongly prefer larger sizes (Killeen, Cate, & Tran, 1993). When animals are given a choice between different amounts, preference is strongly controlled by amount (Neuringer, 1967), and the effect increases with the delay to reward (e.g., Ito, 1985).…”

Food choice in the laboratory pigeon

“…Killeen, Cate, and Tran (1993) found that pigeons have a preference towards peas and popcorn. Similarly, Brown (1969) found pigeons to have a preference for peas.…”

“…Brown (1969) found that pigeons had a tendency to prefer peas, while Killeen, Cate, and Tran (1993) found pigeons to prefer peas and popcorn in Experiment 1A. We looked to further explore these options as well as expand upon the types of foods examined beyond mainly grains and seeds.…”