Lecture 3 - Perception Flashcards

1
Q

What is perception?

A

Experience resulting from stimulation of the senses.

A complex set of processes by which we organise, recognise and make sense of the sensations we receive from environmental stimuli
changes based on added information.
An active process similar to reasoning or problem solving.
occurs in conjunction with actions.

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2
Q

How is human perception different?

A

Other species ‘see’ things that are invisible to us
Unlike humans, most mammals, many birds, and insects, and fish can see ultraviolet light, goldfish see ultraviolet + infrared, snakes can see temperature
Attempts to create artificial forms of perception (machines) have been met with limited success and each time have had problems that could not be solved.

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3
Q

Give an example of this difference

A

Blaschko lines are unique human markings in our skin lines that are very similar to zebra stripes
They are invisible to our visual system but easily to identify for all species that can see ultraviolet light.

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4
Q

Why is it hard for computers to copy human perception?

A

Inverse Projection Problem
- Task of determining the object responsible for a particular image on the retina.
- Involves starting with the retinal image, then extending outward to the source of that image.

Objects can be hidden or blurred
- People can often identify objects that are obscured and therefore incomplete, or in some cases objects that are blurry.

Objects look different from different viewpoints
- Viewpoint invariance.

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5
Q

What are the two approaches to understanding perception?

A

Direct perception theories and constructive perception theories

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6
Q

Describe direct perception theories

A

Bottom-up processing.
Perception comes from stimuli in the environment.
Parts are identified and put together, and then recognition occurs.

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7
Q

Describe constructive perception theories.

A

Top-down processing.
Processing originates in the brain, “top” of the perceptual system.
People actively construct perceptions using information based on expectations.

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8
Q

What is top down processing?

A

Processing starts in the brain
Person’s knowledge, experience, and expectations.

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9
Q

What is bottom up processing?

A

Perception starts with the senses
Incoming raw data
Energy registering on receptors.

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10
Q

Is the perception of pain top down or bottom up?

A

This is a bottom-up process because it depends on stimulation of the receptors. Pain occurs when receptors in the skin are stimulated.
Pain is influenced by what a person expects, how the person directs their attention and distracting stimuli present.

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11
Q

How is top down processing used in language?

A

Top-down processing influences our perception of language based on our individual experience with the language (McGurk illusion see additional materials).
Speech segmentation: Ability to tell when one-word ends, and another begins.
Transitional probabilities: Knowing which sound will likely follow another in a word.

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12
Q

What is Helmholtz’s unconscious inference?

A

Top-down theory to address visual ambiguity

Some perceptions are the results of unconscious assumptions we make about the environment
We use our knowledge to inform our perceptions.

We infer much of what we know about the world

Likelihood principle
We perceive the world in the way that is “most likely” based on our past experiences.

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13
Q

What is Gesalt’s principle of perceptual organisation?

A

The mind groups patterns according to intrinsic laws of perceptual organization based on knowledge about the world.

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14
Q

What is the figure ground principle?

A

There needs to be a distinction between an object and its background

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15
Q

What is the principle of good continuation?

A

Lines tend to be seen as following the smoothest path
Good continuation helps us perceive the rope as a single strand.

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16
Q

What is the law of pragnanz?

A

Principle of simplicity or good figure
Every stimulus pattern is seen so the resulting structure is as simple as possible.

17
Q

What is the principle of similarity?

A

Similar things appear grouped together.

18
Q

What is the modern view of perception?

A

Perception is influenced by common physical properties of the environment.
This means it is based on experience, not innate/intrinsic

Example: Oblique effect
We perceive verticals and horizontals more easily than other orientations.

19
Q

What is scene schema?

A

It is knowledge of what a given scene ordinarily contains.
Cultural differences also influence perception

20
Q

What is bayesian inference?

A

One’s estimate of the probability of a given outcome is influenced by two factors:

  • The prior probability
  • The likelihood of a given outcome.
21
Q

Give and example of the bayesian inference

A

Existing beliefs about the relative frequency of having a cold, lung disease, and heartburn. These beliefs are someone’s priors.

Further data indicate that colds and lung disease are associated with coughing, but heartburn is not. These data contribute to the likelihood.

Taking the priors and likelihood together results in the conclusion that her cough is probably due to a cold (Bayesian Inference).

22
Q

What is experience-dependent plasticity?

A

mechanism through which the structure of the brain is changed by experience.

23
Q

How does movement facilitate perception?

A

Moving in space adds complexity to perception compared to if we remain static.

But moving around a stimulus offers us more views to create accurate perceptions (viewpoint invariance).

24
Q

What is the dorsal pathway?

A

a visual system that stretches from the primary visual cortex in the occipital lobe to the posterior parietal cortex

25
Q

What is the ventral pathway?

A

pathway that leads to the temporal lobe, which is involved with object and visual identification and recognition