Week 5: Two Visual Systems Flashcards
What is the Dorsal stream and Ventral stream go to?
Dorsal stream goes to the posterior prandial cortex and the Ventral stream goes to the inferior temporary cortex
What is the Dorsal and Ventral stream system each described as? What are some of the characteristics of each
Dorsal system: The ‘where’ and ‘how’ system. Visual control movement, egocentric (vision related to you), unconscious
Ventral system: the ‘What’ system, identification of objects and events, allocentric (location in space), conscious
What is the Neurophysiological evidence behind the 2 systems?
Physiological studies in monkeys and imaging studies in human concluded that ventral system is responsible for pattern, form, and colour information whereas dorsal is responsible for motion and spatial information.
They use the same information but use the information differently
What are the Neuropsychological evidences for the 2 systems (Ventral, Dorsal)?
Participant with optic ataxia had an impairment in the dorsal pathway. The participant was able to locate objects but unable to execute motion to pick the item up. More difficulty was experienced in pointing without delay.
There was however no visuospatial or motor control problems
another study looked at a participant with visual agnosia. This was a damage in the ventral stream, where the individual couldn’t identify an image however was able to draw from memory. Furthermore the individual could not recognise its own drawing. Other impairments were that height of obstacles were poorly estimated but the individual was highly proficient at grasping with an appropriate hand orientation.
What is the Psychophysical evidence of the Dorsal and Ventral Systems?
The psychophysical study showed difference between recognition and action in participants.the participant was offered a stimulus (verbal response and motor response). Using the Ebbinghaus illusion, it seemed that verbal response was more influenced by illusion than the motor response. The effect of the illusion was increased with delay between the stimulus and response. (use more from memory
Simply explain a bit about indirect perception
Observer perceives constancies such as size and shape. It was seen that an increase in reduction of information (Remove cues about distance), a more poor size constancy was seen.
Observer takes into account context and stored knowledge to judge size and distance.
What are the implications of the ventral and dorsal systems in sport? Also, what might be a problem?
Most sports rely on the dorsal system yet many drills train the ventral system.
One example may be the goalkeeper joy stick study (Savelsbergh, 2002), which was criticized by: Dicks (2010).
Also research assessing visual anticipation assumed single perceptual process, and single representations. Therefore majority studies ventral streams both lab and field.
How might experts manipulate the 2 systems (Dorsal and Ventral) for better performance?
Athletes may train to empty the mind in situations like penalty and minimise the interference effects of cognitive systems (Ventral stream). They may be able to train oneself to down-regulate the ventral stream in order to maximise effectiveness of the dorsal stream.
