Ventral Visual Systems Research Articles

Direct information on the cutting room floor

Norman's assigning of the constructivist percept-percept coupling approach and the ecological affordances approach to the ventral and dorsal visual systems, respectively, makes a more workable metatheory than each taken separately, but brings both under closer inspection.

Two theories of perception: Internal consistency, separability and interaction between processing modes

Comparisons are drawn between two theories of visual perception and two modes of information processing. Characteristics delineating dorsal and ventral visual systems lack internal consistency, probably because they are not completely separable. Mechanism is inherent when distinguishing these systems, and becomes more apparent with different processing domains. What is lacking is a more explicit means of linking these theories.

Contrasting the Dorsal and Ventral Visual Systems: Guidance of Movement versus Decision Making

It is widely accepted that the ventral visual pathways are involved in the identification of objects and the dorsal visual pathways in the visual guidance of reaching and grasping movements. But there are also situations, such as in a choice reaction time task, in which the subjects must select between actions on the basis of visual cues. This paper uses brain imaging to explore the pathways that are involved. Studies using PET and fMRI show that when subjects learn which actions are appropriate given the visual context, there are learning-related increases in the inferotemporal cortex and the ventral prefrontal cortex to which it projects. An event-related fMRI study shows that the activity in the inferotemporal cortex is time-locked to the presentation of the visual cue and the activity in the ventral prefrontal cortex to the response. Finally two PET studies directly compare the dorsal and ventral systems. In the second of these the subjects either move their finger on a moving target or identify the direction of movement and press one of two buttons to report the direction. When the subjects report the direction there is activity in the middle temporal gyrus and ventral prefrontal cortex. It is suggested that, when subjects must consciously identify the context and decide on the appropriate action, ventral pathways are involved.