Two Visual Systems

Question 1

Dorsal system

Answer 1

The dorsal system tells you where things are and how to move toward them.
It helps you find objects and act on them (like grabbing a cup or dodging a ball).
It works by sending visual information from the back of your brain (where you see things) to the top part of your brain (where you figure out space and movement).
Super simple example:
You see a ball flying toward you — the dorsal system helps you know where the ball is and move your hands to catch it.
Unconscious

Question 2

Ventral system

Answer 2

The ventral system tells you what things are.
It helps you recognize objects, faces, colors, and details.
It works by sending visual information from the back of your brain (where you see things) to the bottom part of your brain (where you figure out meaning).
Super simple example:
You see a ball — the ventral system helps you know that it’s a ball (not a hat, not a dog).

Conscious

Question 3

Dorsal and ventral - direct or indirect

Answer 3

Dorsal - direct
Ventral - indirect

Question 4

Implication for sport

Answer 4

Most rely predominantly on the dorsal system
Avoiding opponents, catching
Many drills train the ventral system e.g. shadowing
Sport skill assessment often tests the ventral system

Question 5

Direct perception

Answer 5

Info in the ambient optic array is picked up by the observer
Observer perceives affordances of objects, not the qualities of objects
Observer activiely explores environment: eye, head and body movements are part and parcel of the perceptual process

Question 6

Indirect perception

Answer 6

Observer perceives consistencies such as size consistency and shape consistency
Increasing reduction leads to poorer size consistency
Observer takes into account context when judging size, distance …

Question 7

Evidence - neuropsychological studies

Answer 7

• physiological studies in monkeys
• imaging studies in humans

Conclusion: 2 visual systems
Ventral: pattern, form, colour info
Dorsal: motion and spatial information.
Overlap in what but differ in why (function)

Question 8

Optic ataxia

Answer 8

Optic ataxia is when a person can see things clearly, but has trouble reaching out and grabbing them correctly.
Their eyes are fine and their hands are fine, but their brain can’t coordinate vision and movement properly.
Super simple example:
If someone with optic ataxia tries to pick up a cup, they might miss it, knock it over, or grab the wrong spot, even though they can see it perfectly.

Damage to the dorsal system
NEUROPSYCHOLOGICAL

Question 9

Visual agnosia

Answer 9

Visual agnosia is when a person can see things, but can’t recognize what they are.
Their eyes work fine — the problem is the brain can’t figure out what the object is.
Super simple example:
If someone with visual agnosia looks at a key, they can see its shape and color, but they don’t know it’s a key — unless they touch it or hear it described.

Damage to the ventral system
NEUROPSYCHOLOGICAL

Question 10

Psychophysical studies

Answer 10

Shows a difference between recognition and action
Participants are offered a stimulus
- verbal response
- motor response
EBBINGHAUS ILLUSION
Verbal response more influences by the illusion than the motor response
Effect of illusion increases with delay between stimulus and response