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PSYC30018: Theme 2: Simon Series (W5-6) > W6 - Reality > Flashcards

W6 - Reality Flashcards

1
Q

Does detecting modulations in colour rely in output of local/distributed neurons

A

Distribution representation, not output of local/individual neurons

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2
Q

What are the 2 evidences to suggest that detecting colour modulation is part of a distributed representation

A
  1. ) Psychophysical sensitivity to chromatic stimuli far better than that of any individual neuron
  2. ) Different neural expansions in Magnocellular and Parvocellular pathways from retina to V1
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3
Q

First evidence that colour modulation is part of a distributed network:

Psychophysical sensitivity to chromatic stimuli > neuronal senstivity. What does sensitivity mean and how does it relate to threshold?

A

More sensitive = Lower threshold level needed to identify stimulus.

We need lower threshold to identify colour than luminance

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4
Q

Colour vs Motion: Neuronal Properties, Which Cells in the LGN, Feedback

A

Colour

  • Population Neurons
  • P cells
  • Feedback between V1 and LGN
    • Feedback takes time
    • Hence, we are not very good at looking at colours move

Motion:

  • Potentially single neurons
  • M cells (Luminance)
  • Little feedback between V1 and LGN
    • Feedback takes time
    • Hence, we are good at detecting luminance motion.
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5
Q

Second evidence that colour modulation is part of a distributed network:

M and P Pathways to Retina Cortex

A

M: Luminance

P: Colour

Both are anatomically distinct

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6
Q

M pathway in Retical Cortical Expansion

A

Retina: Cones in retina has larger receptive field than P

Retina to LGN: 1-to-1 relationship

LGN to V1: Principle point of expansion

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7
Q

P pathway in Retical Cortical Expansion

A

Retina: Cones in retina has smaller receptive field than P

Retina to LGN: Principle point of expansion

LGN to V1: Little (not 1-to-1) relationship between LGN and V1

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8
Q

Is there more feedback between: V1 to LGN, or LGN to V1

A

More feedback between V1 to LGN

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9
Q

What is require to study motion? What do studies of motion detection in chromatic stimui show?

A

Studies of chromatic stimuli (No Luminance): There must be some spatiotemporal interaction (movement in space and time) prior to motion extraction.

Motion detection

  • Primarily on luminance
  • Only in nosiy context does it rely on colour
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10
Q

fMRI study about M and P Pathways

A
  • Cardinal tuning in V1 (Not evident in neurons)
  • Represents some kind of feedback, unlike the single cones of retina, whole V1 has cardinal representation
    • Presumably after feedback of LGN and V1
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11
Q

Why is there more feedback from V1 to LGN?

A

Mediating factor on Parvocellular activity, and then feedback into V1

  • Relating to sense of colour (unique hues) and cardinal space
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12
Q

V4 vs V1

A

V4: Sense of Colour (taking into account context)

V1: Threshold and Hue

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13
Q

How does the unique hue axes differ from cardinal space

A

Unique Hue Axes

Defined around perception of colour

Cardinal Space

Defined upon detactability/excitability of observing a colour

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14
Q

Why is there a difference between a unique hue (our sensation/representation of colour) and that of cardinal space?

A

Basic sense of colour (unique hue) is not predicted by basic properties represented by cones (cardinal space)

  • May be due to feedback from cortex and strong connections between LGN and cortex
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15
Q

Crooper et al. (2013): Colour discrimination: between vs within categories results

A

Discrimination between categories is easier than discrimination within categories.

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16
Q

Is colour vision categorical/continous? Cropper (2013) study overview

A

Discrimination (With colour name) vs Free-Categorization (Without colour names)

17
Q

Is colour vision categorical/continous? Cropper (2013) study results from discrimination task

A

Discrimination: Highly accurate performance (i.e., responding ‘same’ only when the test colour was very similar to the reference colour)

18
Q

Is colour vision categorical/continous? Cropper (2013) study results from categorical task

A

Free-Categorization: Everyone their own categorical structure and much as the broader > No categorical boundary effect

19
Q

Is colour vision categorical/continous? Cropper (2013). When is colour categorical

A

When it included language

20
Q

Is colour vision categorical/continous? Cropper (2013). Conclusion

A

Descripion and Action does not affect perception.

Rather, perception affects description and action

21
Q

Taken together, what does all the vision studies suggest?

A

We still lack a predictive and quantitative model of how we see simple visual stimuli.

22
Q

What is syneaesthesia

A

Involuntary conjoint perception across two modalities

23
Q

Is synaesthesia objective?

A

No.

(a) Subjective/Unique
(b) Consistent

Experience

24
Q

What is the most common syneaesthesia

A

Colours (70%)

25
Q

How do hallucinogens work

A

Mimics NT serotonin.

Increasing 5H-T = Increase cortical activity = reduce inhibition

26
Q

What is induced when inhibition is reduced and cortical activity is increased in system

A

Visual and auditory hallucination

Impairs high-level, not low-level, motion perception.

27
Q

Define motion detection (What does it require). How do hallucinogens affect motion detection

A

Motion Detection (Biological motion, flow fields, structure from motion)

Hierarchical system: Requires integration from simple isolated vecotrs into coherent representation.

Disuprts integration process.

28
Q

Study: Carter et al. (2004) Motion Perception and Psilocyblin. What were the 2 tasks

A
  1. Right motion contrast sensitivity
  2. Motion Integration sensitivity
29
Q

What is simple motion detection

A

Motion Vector

  • Indicates direction and speed of image in retina
  • Most likely luminance, could be colour
30
Q

Study: Carter et al. (2004) Motion Perception and Psilocyblin. What were results from Task 1

A

Right motion contrast sensitivity

  • Rigid
  • Dots move same direction

Results

  • Can do with basic motion detection
31
Q

Study: Carter et al. (2004) Motion Perception and Psilocyblin. What were results from Task 2. Conclusions from Task 1 and 2.

A

2. Motion Integration sensitivity

  • Non Rigid
  • Global
  • More dots with differing movements
    • Basic motion detector must be integrated into global precept

​Results

  • Integration critically affected
  • Therefore, psilocyblin affected integration and failure to inhibit.
32
Q

What is relationship between hallucinogenics and schizophrenia

A

Some similarities to psychosis

  • In SZ patents, simple visual task requiring less integration led to better performance (due to context)
33
Q

Study: Dakin et al. (2005) Contrast of central disk and SZ patients. Compare the results of SZ and controls

A

Controls: Worse

(a) Stronger contextual suppression
(b) Vulnerable to ‘contrast’ illusion
(c) Less accurate at judging contrast where contrasts disrupts judgement

SZ: Better

(a) Weaker contextual suppression
(b) Less vulnerable to ‘contrast’ illusion
(c) More accurate at judging contrast since contrasts does not disrupt judgement

34
Q

What is schizotypy and what is it linked with?

A

At high levels, mirrors SZ.

High positive schizotypy (wild day dreams, etc) linked to hallucinations

35
Q

Study: Partos, Cropper, and Rawlings (2016): Schizotypy and image meaning. Study Overview

A

Present random array of white dots and instructed dots show something meaningful .

36
Q

Study: Partos, Cropper, and Rawlings (2016): Schizotypy and image meaning. Study Findings and Conclusion

A

Higher psychoticism, neuroticism, hallucination-proneness

  • Perceived more meaningful images of complex nature of dots
  • Therefore, schizotypy associated with perceiving complex meaning in random visual noise.

PSYC30018: Theme 2: Simon Series (W5-6) (3 decks)

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