To study cognitive flexibility in nonhuman animals, researchers have used several different paradigms that preserve the essential properties of human tasks. In that same vein, we explored pigeons’ cognitive flexibility to concurrently perform two complex categorization tasks: a numerosity discrimination (where number was the relevant dimension and variability was the irrelevant dimension) and a variability discrimination (where variability was the relevant dimension and number was the irrelevant dimension). Examples of the stimuli can be seen on the left.
Pigeons learned to perform these tasks and showed high accuracy levels. The flexibility of pigeons’ behavior was evidenced by their accurate and rapid, on-demand switching between tasks within training sessions.
In addition, we discovered an intriguing interplay between the numerosity and variability discriminations. Pigeons were affected by the variability of the items when performing the numerosity discrimination and by the number of items when performing the variability discrimination, but in a quite systematic way. Pigeons more accurately performed the numerosity task with arrays displaying high variability than with arrays displaying low variability and they more accurately performed the variability task with arrays containing many items than with arrays containing few items. In addition, when the magnitudes of the relevant and irrelevant dimensions were congruent on a given trial, pigeons’ accuracy was higher than when the magnitudes were incongruent. Thus, the irrelevant dimension facilitated the target discrimination performance when its magnitude matched the magnitude of the correct choice and impaired the target discrimination performance when its magnitude did not match the magnitude of the correct choice.
Castro, L., & Wasserman, E. A. (2016). Executive control and task switching in pigeons. Cognition, 146, 121–135. https://doi.org/10.1016/j.cognition.2015.07.014
In a later study we examined whether pigeons could flexibly shift their attention from one set of features that were relevant in one categorization task to another set of features that were relevant in a second categorization task. Critically, members of both sets of features were available on every training trial, thereby requiring that attention be differentially deployed on a trial-by-trial basis based on contextual information.
The pigeons not only learned to correctly categorize the stimuli but, as training progressed, they concentrated their pecks to the training stimuli (a proxy measure for attention) on those features that were relevant in a specific context. The pigeons selectively tracked the features that were relevant in Context 1—but were irrelevant in Context 2—and they selectively tracked the features that were relevant in Context 2—but were irrelevant in Context 1. This highly adept feature tracking requires disengaging attention from a previously relevant feature and shifting attention to a previously ignored feature on a trial-by-trial basis. Pigeons’ adaptive and flexible performance provides strong empirical support for the involvement of focusing and shifting attention under exceptionally challenging training conditions.
See one of our favorite pigeons performing this task. Make sure that you get the written description to understand the video and keep up with the pigeon.
The debate remains open as to whether pigeons’ performance results from the engagement of “true” executive function--involving the capacity to actively and rapidly suppress the processing of irrelevant information and to preferentially process relevant information in order to satisfy the demands of the prevailing task--or from more basic, bottom- up, associative mechanisms that do not require such attentional control. Similarly, yet to be established is whether higher-level avian brain structures, like the avian nidopallium caudolaterale (NCL), are necessary for mastery of tasks like the one used here or whether pigeons’ success is the result of more basic associative mechanisms achieved by lower-level neural systems.
Castro, L., Remund Wiger, E., & Wasserman, E. (2021). Focusing and shifting attention in pigeon category learning. Journal of Experimental Psychology: Animal Learning and Cognition, 47(3), 371–383. https://doi.org/10.1037/xan0000302
O'Donoghue, E., & Wasserman, E. A. (2021). Pigeons proficiently switch among four tasks without cost. Journal of Experimental Psychology: Animal Learning and Cognition, 47(2), 150–162. https://doi.org/10.1037/xan0000287