Many researchers study how nonhuman animals visually perceive the world; to date, however, only certain types of experiments have been possible, given the limitations of animal learning and response capabilities. With funding from the National Science Foundation, Drs. Cavanagh and Pepperberg are investigating visual processing in a Grey parrot named Alex, who can vocally answer many questions at the level of a 4- or 5-year-old human child. The investigators are examining visual attention beginning with basic studies of visual illusions, i.e., stimuli that appear to humans to vary in size but in reality do not. These experiments leverage Alex's ability to vocally report the color of the larger or smaller of two items or reply 'none' if no difference is seen. Such experiments are accompanied by attention tasks in which two targets must be detected in a rapid stream of items. The targets will be the digits 1 through 8 that Alex can recognize. For humans, the second target in such a stream is often lost if it follows the first too closely. This interference from the first target is called the 'attentional blink' and it is a measure of the speed with which attention can switch from one target to the next. Do parrots, which are prey species that must monitor for sequential predator movement and attack, have the same speed of attentional switching as humans? Or will this task reveal differences in cognition between birds and humans? Drs. Cavanagh and Pepperberg are investigating a broad range of visual tasks to determine which attention abilities share the same underlying mechanisms in birds (grey parrots) and humans and which do not. Similarities between these two species, with very different brain sizes, will allow us to understand which components of cognition can be implemented with smaller scale neural architecture. Differences will indicate the components that require greater brain size and/or complexity. The data will guide future comparisons with other species and providing insights into the structure and function of the human brain and for the design of artificial visual processors.
