Potentiation instead of overshadowing in the pigeon

Taste potentiates color-sickness associations in pigeons and quail

“…This pattern of statistically reliable differences persisted through the first three color tests but thereafter it was attenuated by extinction. Thus the present results are similar to those obtained by Clarke et al (1979) except that reliable conditioning of the color cue alone was observed in the present experiment.…”

“…Both Clarke et al (1979) and I found in pigeons that the color cue was potentiated by the taste cue, while Wilcoxon et al (1971) reported that, in quail, the color cue overshadows the taste cue. However, a reexamination of Wilcoxon's data suggests that they are susceptible to an alternative interpretation more in keeping with the pigeon results.…”

“…Wilcoxon et al (1971) have proposed that, for quail, visual cues are more important than taste cues in food selection. For the relative salience of visual and taste cues to be opposite in rodents and birds, at least, seems reasonable: Rodents have relatively poor vision and must rely heavily on smell and taste for finding and recognizing food, while quail and other birds have well-developed visual abilities and rely more heavily on vision in foraging for food and drink.Recently, however, evidence has been obtained in hawks (Brett, Hankins, & Garcia, 1976)and in pigeons (Clarke, Westbrook, & Irwin, 1979) that the pattern of cue utilization in these birds differs markedly from that suggested by Wilcoxon et al (1971) for quail. Unlike quail, both hawks and pigeons readily acquired taste aversions but seemed to require a special condition to form visual aversions.…”

“…Recently, however, evidence has been obtained in hawks (Brett, Hankins, & Garcia, 1976)and in pigeons (Clarke, Westbrook, & Irwin, 1979) that the pattern of cue utilization in these birds differs markedly from that suggested by Wilcoxon et al (1971) for quail. Unlike quail, both hawks and pigeons readily acquired taste aversions but seemed to require a special condition to form visual aversions.…”

A response rule for positive and negative stimulus interaction in associative learning and performance

“…The overshadowing effect is known to be especially strong when the salience of CS X is weak relative to the salience of CS A (i.e., CS A is said to overshadow X based on its higher salience). However, some studies have also reported that, under certain conditions, the presence of A can facilitate, rather than undermine, the acquisition of conditioned responding by X, an effect known as potentiation (e.g., Clarke, Westbrook, & Irwin, 1979;Durlach & Rescorla, 1980;Rusiniak, Hankins, Garcia, & Brett, 1979). Analogously, blocking (Kamin, 1968) consists of the weak response that is produced by a CS, X, when it is paired with the US in compound with a second CS, A, which was previously paired with the US on its own.…”