Unit 1

Visual Agnosia

a disorder where people can perceive objects, but cant identify or recognize them

Stimulus-Behavior

sensory input leads to behavior)

Stimulus - physiology

(sensory input leads to physiological changes in body like neurons firing, or changes in brain activity)

Physiology-behaviour

relationship that links physiological responses to boldly states like actions and reactions

Rat man demonstration

Participants are shown ambiguous images that can be interpreted as rat or man, depending on what they focus on. When people are primed with a man or man image beforehand, they are more likely to see the corresponding image. This shows that perception is shaped a lot by context.

Oblique effect

people are better at perceiving and recongitizing vertical and horizontal lines than at diagonal lines

Signal detection theory

consider situations where decisions are made under conditions of uncertainty or bias influences.

• if a person tries to identify a signal under uncertainty they can get a

  1. Hit

  2. Miss

  3. False alarm

  4. Correct Rejection

D’ (d prime)

measures distance between the hits and false alarms

Neuron movement

• Sensory neurons go from PNS→ CNS

• Motor neurons go from CNS → PNS

Electricity in the neuron

• Intracellular fluid has a negative charge (lots of anions and a few K+)

• Extracellular fluid has a positive charge (lots of cations Na+)

neuron resting charge

-70mV

Action potential process

1. Rising phase 

• Signal received 

• Charge goes from -70 to -55

• Sodium channels open up and Na+ rushes in

• Neuron depolarizes to +40mV

2. Falling Phase

• Sodium channels close

• Potassium channels open and potassium rushes us to bring neuron back to negative state

• Neuron briefly hyperpolarizes. 

3. Recovery phase

• Sodium potassium pump kicks out Na and brings back in K+

• Returned to resting state of -70mV

Rate law

 intensity of stimulus is communicated by how frequently action potentials are generated.

All or none law:

the strength of the action potential does not change based on the stimulus intensity, if the stimulus is strong enough to trigger a potential, the signal stays the same as it moves down the neuron. 

•  Brighter light does NOT mean more intense signal

Centre surround antagonism:

when both areas of the centre surround receptive field are stimulated there's an intermediate response.

More inhinbition appears

darker

Myopia treatment

glasses with concave lens

Hyperopia treatment

glasses with concave lens

Rods

• Fast 

• Good night vision 

• No colour perception 

• Low acuity 

• Good vision in peripheral

Cones

• Slow

• Needs brighter light

• High acuity in central vision 

• Conveys colour info

Vision in the dark

1. Light causes retinal molecule to isomerize

2. Retinal separates from opsin - (pigment bleaching)

3. Retinal and opsin must combine again 

4. Cone regeneration takes 6 mins

5. Rod regeneration takes 30 minutes

I stehre convergence in the fovea?

No, cones have 1:1 ratio with ganglion

• rods have 120:1 outside fovea

• cones have 6:1 outside fovea

Purkinje shift

The shift from cone-mediated color vision to rod-mediated vision as light decreases. This shift causes colors to appear differently under dim light, with blue appearing brighter than red.