From 1999 to 2001, I was awarded a postdoctoral fellowship (National Research Service Award) from NIMH to explore visual perception and cognition in pigeons in Robert Cook's laboratory at Tufts University. One line of research focused on relational conceptual behavior. While many animals seem able to respond to certain stimulus situations with a limited set of behaviors, it is also clear that complex animals, such as birds and mammals, can generalize beyond the training context and abstract their learned behavior to novel situations. One of the most powerful forms of abstraction is relational behavior, such as discrimination of Same and Different. We have provided a variety of evidence that pigeons can apply the Same/Different concept to a wide range of situations (e.g., Blaisdell & Cook, in prep). A second line of research focused on visual perception in pigeons. While much is known about the psychophysics of vision and the underlying visual processes in primates, comparatively little is known about avian visual systems. Avian species, such as the pigeon, pose an interesting group with which to compare primates, particularly because avian vision is complex and in some ways superior to primate vision. For example, pigeons have very complex retinal structures, two cone-dense fovea in each retina (as opposed to the single fovea of primates), visual sensitivity extending infrared to ultraviolet wavelengths, and they are true pentachromates (i.e., they have five cone types, as opposed to the three types as in trichromatic primates). However, birds lack an isocortex, thus, many of the visual processes that are handled by the cortex in primates are handled by other structures in birds. Thus, pigeons are ideally suited subjects for teasing apart the relationships between psychophysics and neural processes of vision through comparative analysis with primates. Some of the issues we have explored so far include the contributions of motion to object perception (Cook, Shaw, & Blaisdell, 2002; Cook, Katz, & Blaisdell, in preparation), attentional processes in vision (Blaisdell, Katz, & Cook, submitted), and comparative face perception (Blaisdell & Cook, in preparation). I plan to continue to explore visual perception and cognition in the pigeon, and to begin investigations of their underlying neural bases.

     Another focus of the pigeon lab is the acquisition of spatial relationships between paired events and the integration process that fuses these representations together. Physicists have long been aware of the equivalency of relationships between space and time. Recent advances in neuroscience, specifically a better understanding of the similar roles of the hippocampus in spatial and temporal processing, suggests a unified or shared psychological processes for both space and time. In fact, it is possible that there is a single psychological and neural code for both physical dimensions. A valuable method used in psychology for establishing that a single process underlies multiple behavioral phenomena is to demonstrate that the nature of the behavior for one phenomenon is isomorphic to that of another phenomenon. Thus, if space and time are subsumed by the same psychological process, then behavior in the spatial domain should react to experimental manipulations in the same manner as behavior in the temporal domain. We reported data (Blaisdell & Cook, 2005) supporting this position by extending the findings of the temporal coding hypothesis (see Rat Research) regarding the integration of temporal maps, by establishing a similar effect for the integration of spatial maps. In an analog to Matzel et al.'s (1988) sensory preconditioning experiment, pigeons were trained to search for hidden food in an open field apparatus. Pigeons were trained in separate phases on an A-B and a B-Goal spatial relationship, where A and B were visual landmarks colored blocks of wood (a red 'L' and a blue 'T', respectively) and the Goal was food hidden in a specific location (one of 16 food cups). Thus, A-B and B-Goal pairings were the preconditioning and conditioning treatments, respectively (see figure to the right). When presented with Landmark A (the red 'L') at test, pigeons searched for the goal most often at a location consistent with their having integrated the A-B and B-Goal experiences (see figure and graph to the right). This integration allowed subjects to compute a novel A-Goal spatial relationship.

     We recently replicated and extended the results of Blaisdell & Cook (2005) using an automated touch screen task (Sawa, Leising, & Blaisdell, 2005). Automated touch screen tasks provide many benefits over open-field tasks, for example, we can conduct many more trials per daily session, present a wider range of experimental and control conditions, we can test multiple birds simultaneously (currently four at a time), and we have access to a much larger reserve of controlled visual stimuli to serve as landmarks. Consequently, with a touch screen we are able to collect many more data in a short amount of time, and learning can progress more rapidly (thus, each phase of training can be conducted over days instead of weeks). Furthermore, many more types of trials and visual stimuli can be used within a single subject, allowing us to run many more control conditions and gain much more information with each subject. We also have space to run open-field versions of key touch screen experiments to verify the generality of our touch screen data and support the claim that it applies to spatial processing.