Pigeons deploy selective attention to efficiently learn a stagewise multidimensional visual discrimination task

Stepwise learning of compound multidimensional visual stimuli by sorting out the dimensions of which they are composed in pigeons

Pigeons (Columba livia) were trained on a stage-wise go/no-go visual discrimination task. Sixteen compound stimuli were created from all the possible combinations of two stimulus values from four separable visual dimensions: shape (circle/square), size (large/small), line orientation (horizontal/vertical), and brightness (dark/light). Starting with 1 S + and 1 S - that differed in all four-dimensional values, in our later steps, we added S - stimuli one by one, sharing at first 1, then 2, and then 3 dimensions with S + by sorting them out. When the pigeons had clearly shown attending to each of four dimensions, we presented all 16 stimuli. In this last stage, the pigeons correctly rejected most of the S - stimuli despite seeing them for the first time. Thus, to discriminate 16 unique multidimensional stimuli, it was not necessary to learn all of them as compound stimuli in such an approach. However, the 4 learnt dimensions did not give fully comprehensive information about all the new and unique compound stimuli presented in the last stage. Mistakes were associated with similarity to S + and with the order of dimensional learning. Most pigeons made mistakes in the discrimination of S - stimuli that shared 3 (some shared two) dimensions with S + . The knowledge of the first-learned dimension of compound stimuli was less reliable than the dimensions learned in the last stage.

The effect of dimensional reinforcement prediction on discrimination of compound visual stimuli by pigeons

We trained eight pigeons (Columba livia) on a stagewise go/no-go visual discrimination task. A total of 16 visual stimuli were created from all possible combinations of four binary dimensions: brightness (dark/bright), size (large/small), line orientation (vertical/horizontal), and shape (circle/square). In the first stage, we presented S + and four S- stimuli: sharing one (brightness), two (brightness and orientation), three (brightness, orientation, and size), or no dimensional values with S + . In the second stage, all 16 stimuli were presented. In the first stage, stimulus discrimination was controlled by the number of dimensional disparities between non-rewarded stimuli and a rewarded one rather than by stimulus dimensional salience, whereas at the beginning of the second stage, pigeon behaviour was controlled mainly by dimensional reinforcement expectancy learned in the first stage. At the beginning of the second stage, pigeons correctly rejected 6-8 of 11 new added S- stimuli. A significant inverse correlation between the number of S- stimuli sharing dimension values with S + in the first stage and the dimensional discrimination ratios at the beginning of the second stage was found.

Endogenous and exogenous control of visuospatial selective attention in freely behaving mice

Visuospatial selective attention has been investigated primarily in head-fixed animals and almost exclusively in primates. Here, we develop two human-inspired, discrimination-based behavioral paradigms for studying selective visuospatial attention in freely behaving mice. In the ‘spatial probability’ task, we find enhanced accuracy, sensitivity, and rate of evidence accumulation at the location with higher probability of target occurrence, and opposite effects at the lower probability location. Together with video-based 3D head-tracking, these results demonstrate endogenous expectation-driven shifts of spatial attention. In the ‘flanker’ task, we find that a second stimulus presented with the target, but with conflicting information, causes switch-like decrements in accuracy and sensitivity as a function of its contrast, and slower evidence accumulation, demonstrating exogenous capture of spatial attention. The ability to study primate-like selective attention rigorously in unrestrained mice opens a rich avenue for research into neural circuit mechanisms underlying this critical executive function in a naturalistic setting.

The authors describe behavioural tasks for the study of primate-like, endogenous and exogenous control of visuospatial selective attention in freely behaving mice.

Pigeon category learning: Revisiting the Shepard, Hovland, and Jenkins (1961) tasks

In a seminal study, Shepard, Hovland, and Jenkins (1961; henceforth SHJ) assessed potential mechanisms involved in categorization learning. To do so, they sequentially trained human participants with 6 different visual categorization tasks that varied in structural complexity. Humans' exceptionally strong performance on 1 of these tasks (Type 2, organized around exclusive-or relations) could not be solely explained by structural complexity, and has since been considered the hallmark of rule-use in these tasks. In the present project, we concurrently trained pigeons on all 6 SHJ tasks. Our results revealed that the structural complexity of the tasks was highly correlated with group-level performance. Nevertheless, we observed notable individual differences in performance. Two extensions of a prominent categorization model, ALCOVE (Kruschke, 1992), suggested that disparities in the discriminability of the dimensions used to construct the experimental stimuli could account for these differences. Overall, our pigeons' generally weak performance on the Type 2 task provides no evidence of rule-use on the SHJ tasks. Pigeons thus join monkeys in the contingent of species that solve these categorization tasks solely on the basis of the physical properties of the training stimuli. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Poxvirus Infection in a Colony of Laboratory Pigeons (Columba livia)

Pigeons (Columba livia) are used in biomedical research for studies of vision, cognition, neuronal pathways, and spatial orientation. Because there are few commercial laboratory sources, research pigeons are typically acquired from local fancier breeders or bred onsite. For acquired pigeons, the health and vaccine status is often unknown. A juvenile pigeon, born onsite and living in an enclosed outdoor loft, presented with small, bleeding, wart-like lesions on the medial aspects of digits 1 and 4. Topical treatment was initiated. Within a week, 4 fledglings were reported for small, dark papular lesions on the face, head, neck, and beak, and shortly thereafter, 2 additional juvenile pigeons developed similar lesions. The fledglings were euthanized, and histologic examination revealed numerous intralesional eosinophilic cytoplasmic viral inclusions (Bollinger bodies) confirming a diagnosis of poxvirus infection, likely pigeon pox. Although usually self-limiting, pigeon pox can cause moderate to severe lesions in fledgling and juvenile birds. Vaccination with a modified live poxvirus labeled for chickens was used to create herd immunity to pigeon poxvirus. Since vaccination of our entire flock and implementation of more stringent health protocols, all lesions have resolved, and no new lesions have been noted.