A prominent model of categorization (Ashby, Alfonso-Reese, Turken, & Waldron, 1998) posits that 2 separate mechanisms—one declarative, one associative—can be recruited in category learning. These 2 systems can effectively be distinguished by 2 task structures: rule-based (RB) tasks are unidimensional and encourage analytic processing, whereas information-integration (II) tasks are bidimensional and encourage nonanalytic associative learning. Humans and nonhuman primates have been reported to learn RB tasks more quickly than II tasks; however, pigeons and rats have shown no learning speed differences are thus believed to lack the declarative system. In the present trio of experiments, we further explored pigeons’ dimensional category learning. We replicated the finding that pigeons learn RB and II tasks at equal speeds. Further, we found that stimulus generalization performance was equivalent on both tasks. We also explored the effect of switching from one task to another. Task switches between phases of training as well as within individual training sessions posed little difficulty for pigeons; they quickly and flexibly switched their categorization responses with no cost in choice speed or accuracy. Together, our data indicate that, although pigeons may lack the capacity to form explicit dimensional rules, their associative learning system is both powerful and flexible. Further exploration of this associative system would help us better appreciate possible contributions of the declarative system.
Both humans and pigeons are highly adept at task switching. However, unlike humans, pigeons do not show measurable switch costs: decreased accuracy and/or increased response times when required to switch tasks on successive trials. This striking disparity suggests that humans and pigeons may succeed at task switching via different means: humans may rely on a combination of executive control and associative learning, whereas pigeons may rely solely on associative learning. Here, we further explored the limits of pigeons' associative learning in an expanded task-switching paradigm. We trained pigeons to switch among four tasks, each signaled by two redundant types of task cues. The pigeons benefited from the availability of both task cues despite their redundancy: their accuracies were higher when both cues were available than when only a single cue was available. Additionally, we assessed the possibility that the lack of switch costs reported in the pigeon literature might stem from methodological discrepancies between pigeon and human task-switching paradigms. Across experimental phases, we modified pigeons' trial structures to more closely mimic those typically used in human task-switching research. Despite these modifications, pigeons did not display switch costs, consistent with their sole reliance on associative learning. Overall, our data highlight the power and flexibility inherent in the pigeon's associative learning system.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.