Vision 3

Perception - processing stimuli from the self or environment.

Cognition - the mental process by which external or internal input is transformed, reduced, elaborated, stored, recovered, and used.

• Involves a variety of functions such as attention, memory processing, decision-making, reasoning, problem-solving, imaging, planning and executing actions

Motor behaviour - the planning and execution of actions.

"Response activation" theory predicts that non-target objects activate actions.

Condition 1: participants were able to inhibit the visual processing of the non-target object in the slow response time condition. This resulted in net response inhibition, causing the trajectory of the movement to veer away from the non-target.

Condition 2: in the quick response time condition, however, participants did not have enough time to inhibit the target object. This resulted in a net activation of the action that veered towards the non-target object.

(Welsh & Elliot, 2004).

Task - participants required to aim penalty kick to one of two target locations.

60 trials:

• 20 trials 'no goalkeeper'
• 20 trials 'goalkeeper'
• 20 trials 'knowledgeable goalkeeper'

Measures:

• Performance: hits, misses, failures
• Accuracy: absolute variability from target centre and goal centre
• Variability: variable error from target centre and goal centre
• Ball speed: distance to goal (m) / foot contact to goal contact time (s)

Questions to think about:

Results: was performance influenced by the presence of the goalkeeper?

Discussion: do the authors relate their results to any theories?

• Response activation theory (Welsh & Elliot, 2004)
• Ironic effects theory (Wegner, 1994)

Do the authors make any applied recommendations?

• Practice in the presence of a goalkeeper
• Optimise gaze control during practice
• Longer waiting time before executing the penalty (Jordet et al., 2009)

V1:

• Simple object orientations and shapes
• Global organisations of scenes
• Main connection from the LGN of the thalamus

V2: 

• Receives connections from V1
• Neurons in this region respond to slightly more complex properties such as contours and figure-ground segregation
• Also has connections to dorsal and ventral pathways

V3:

• Responsible for processing complex combinations of visual stimuli
• Contains stronger connections to dorsal and ventral pathways and weaker connections from V1

V4:

• Encodes stimulus saliency and colour
• Also has shown to be more responsive to selective attention than other areas (Moran & Desimone, 1985)

V5:

• Located along the ventral pathway in the temporal lobe
• Contains neurons that are responsive to the direction of motion
• Also contains strong connections to other cortical areas

Step 1: object segregation - i.e. figuring out what, in a complex scene, are the individual objects.

Step 2: object recognition - mapping the object to something that is already known.

Laws of:

• Figure-ground segregation
• Similarity
• Proximity
• Closure
• Continuation
• Common fate

Object segregation:

• Contours and grouping cues
• Occurs largely automatically

Once you have performed object segregation and can see the objects as distinct from the background and other subjects, does that mean you have recognised it?

• The two eyes have a slightly different image of the world on the retina (retinal disparity)
• The close of an object is to you, the greater the difference in the two images
• The brain can use this retinal disparity information to calculate how close the object is to you
• This information becomes less effective as objects get further away; it is primarily useful for objects within arm's distance
• The ability to use binocular disparity develops in children by about 2 years of age and if your eyes do not work together properly during that time period, then binocular disparity will not develop

• Occlusion
• Shading
• Shadows
• Aerial perspective
• Linear perspective
• Height in plane
• Familiar size