Natural life has evolved by using vision to provide the most useful cues for a successful adaptation of the vast majority of living organisms. Foraging and prey hunting, as well as partner selection, are in fact often based on individuals searching around their environment in order to find the right visual configuration that matches a given template. Specific patterns of textures, motion, colors and other visual features are stored somewhere in the brain to be matched with contingent visual experience for recognition and reaction. Such a template, that I assume to be motivationally-activated, is in many cases genetically inherited, is both flexible and rigid to guarantee reliable rates of success. This might be true for classes of living organisms far away from the complexity of mammals, like reptiles or insects, or even taxonomically inferior species. Visual search is so strongly rooted in nature that the amazing phenomenon of camouflage has evolved to balance it.
The study of search constitutes a paradigm that may potentially answer scientific questions about the visual system in general as well as its relationship with other behavioral systems. On the one hand manipulating attention in search displays permits the mechanisms of visual selective attention to be disentangled. On the other hand, since different displays are dealt with differently by the visual system, one can devise optimal configurations of stimuli to investigate the way visual objects are formed and segregated from other objects and the background.
Such a general framework provides a general clue to what my research interests are. I have been carrying on with this topic since 1997, right before my PhD, when I was research assistant at the lab of Michael Morgan, in London. In my thesis project, done in Istituto di Neurofisiologia\del CNR) and Rome Universita` degli Studi “La Sapienza”) under the supervision of David Burr, I dealt with the problem of the integration of information in multi-element displays. Currently, I am working under the supervision of Preeti Verghese in research project generated from our respective earlier work, with a common ground in search and attention experiments, trying to dissect the process of visual search, its counterpart of selective attention, and the problem of information integration. It is our long term goal to answer some of the general questions related to object integration and segregation and their relationship with attention.
During this time, we have been performing a series of psychophysical studies using visual search paradigms where we proposed that perceptual performance as measured is search tasks uses task-related strategies that are often optimal for the task. In particular we have initially shown that search tasks are accomplished by mechanisms that integrate information through parallel architectures where physical signals (orientation, color, luminance) carried by individual local elements can be summed first, and the result of such integration is delivered in the form of a response (i.e. is the tower leaning clockwise or counterclockwise?). Alternatively, under other conditions, such as a task where the subject has to indicate which is the tilted element, the integration of information rule can be switched to one that will pick the response according to the element that has the maximum tilt. Since the visual system is noisy, with various noise sources at different levels of the system, we used techniques that allowed us to quantify the overall variability (by noise I mean receptorial and/or neural variability that introduces limitations in sensory systems). Changing our experimental setup only slightly, we have been able to observe what does occur when cues to selection are provided, what is commonly assumed to be ‘attention’. Generally cues displayed at the time of the stimulus are effective in excluding any detrimental effect of distractors on performance. Our current effort is to find, using psychophysical techniques, the functional and neural mechanisms allowing such an highly efficient attentional selection.
Details on the results of these studies can be found through the references provided in my cv.