Learning, short-term implicit memory and sequential dependencies in behaviour.

In virtually every choice task studied over the last fifty years it has been shown that the responses produced by participants are not sequentially independent: the current response depends on the history of previous responses and previous stimuli. These dependencies reflect a form of implicit, short-lived memory mechanism. To understand the nature and function of this mechanism, in this project we study a variety of choice tasks with simplified stimuli, for example visual search in displays of simple geometrical objects, and investigate the properties of the memory by conducting time series analysis and dynamic system modeling of reaction times and errors. These studies are inspired by the conjecture that the observed behaviour is influenced by an elementary learning mechanism that serves to extract regularities from the environment and predict future outcomes.

Related Publications

Martini, P. (2010). System identification in priming of pop-out. Vision Res, 50, 2110-2115.

Maljkovic, V., & Martini, P. (2005). Implicit short-term memory and event frequency effects in visual search. Vision Res, 45 (21), 2831-2846.

Perception and memory with natural scenes and object categories

Our abilitiy to recognize and remember objects and scenes is impressive and remains unmatched by machine algorithms. Historically, much research has been devoted to understanding early vision with artificial stimuli, such as sinusoidal gratings, textures etc. Over the years this research has produced an impressive body of knowledge that encompasses the behavior, physiology and anatomy of mammals. However, it has become increasingly clear that object recognition, often called more generally high-level vision, is not a simple generalization of early visual mechanisms. The more recent research in vision has seen a shift of emphasis towards more natural stimulus categories, such as faces, objects and scenes, and towards a more comprehensive context that emphasizes the influence of memory, attention and decision processes. This project is concerned primarily with the characterization of factors that influence the perception and memory of objects, faces and scenes in the short-term, such as emotional valence, temporal exposure and shifts in decision criteria that accompany the manipulation of these variables.

Related Publications

Martini, P., & Maljkovic, V. (2009). Short-term memory for pictures seen once or twice. Vision Res, 49 (12), 1657-1667

Martini, P., McKone, E., & Nakayama, K. (2006). Orientation tuning of human face processing estimated by contrast matching in transparency displays. Vision Res, 46 (13), 2102-2109.

Maljkovic, V., & Martini, P. (2005a). Short-term memory for scenes with affective content. J Vis, 5 (3), 215-229.