P&A Flashcards
Evolutionary needs of P&A
- Find food
- Avoid danger
- Reproduction
What is a modality?
A class of stimulus (energy transmitted) and the specialised receptors that ‘sense’ that energy, all perception occurs within certain modalities.
Why can the perceptual system be tricked?
Because the system often ‘estimates’, we have evolved to rapidly extract useful info from the environment.
What’s the more modern overall model corning the way we perceive and act?
Sample info - process info -interact with the world (in a loop)
What is the classic view of perception? Why is this no longer so relevant?
There is a distinction between perception and action in the classic model sensation leads to perception and separately cognition leads to action.
However the lines between perception and action are arbitrary - where does action begin and perception end.
Examples of a perceptual Energy?
Chemical energy i.e. taste, smell
Heat and tactile energy
Energy from waves of air pressure (audition)
What are the differences between light and sound energy that mean bats and dolphins are more adapted to using it?
Sound is present at all times (bats hunt in the dark)
Sound travels faster underwater (dolphins inhabit water)
What is filtering?
Active process of selectively keeping some information , and discarding others
Example of filtering in the eye?
The fact it uses only the visible light part of the spectrum.
What is sampling?
The active seeking of useful information
Are eye movements an example of filtering or sampling?
Sampling (looking for info)
Why is perception and action important to study?
Help humans with impairments in visuomotor activities i.e stroke survivors
What did Smith et al (2015) show (stroke patients)?
They developed novel computerised tools to assess whether stroke survival patients had adequately compensated for their impairments, this has implications on whether they could be allowed to drive in the future, driving offering a larger QoL.
What did Yarbus (1967) say about eye movements?
Human eyes fixate on those elements of a visual scene that carry essential and useful information.
Fixate for longer on more useful info, people who think differently see differently
- Related to the task
Model of P&A using eye-movements as an example?
Motor commands sent to eye to move - visual info sampled from new point of fixation - info informs future eye-movements - Loop back to start.
What are the different types of eye movements?
Conjugate movements (both eyes in same direction):
- Saccades
- Fixation
- Smooth pursuit
- Vestibulo-Ocular reflex
Disconjugate (different directions)
- Vergence
Most recent way to measure eye movements?
Electro-oculography
What are saccades?
Rapid ballistic eye-movements, very short duration (15-100ms)
The most frequent movement we make
What is saccadic suppression?
The mechanism by which we do not see motion blur during saccades - as we are effectively blind during saccades.
What is fixation?
Time where the eyes focus on one area in order to allow us to absorb the information from that area:
Not completely still as photoreceptors and neuronal connections would adapt/fatigue if completely still. (red dot test - Troxler effect)
Micro-saccades/ocular drifts and ocular tremors keep this from happening.
What is smooth pursuit movements? How are they accomplished?
Smoothly follow a moving target
Requires the system to make predictions about where the target will be moving
What is the vestibular ocular reflex?
The interaction of the vestibular system and eye movements when the head is moving - counter rotates the eye when the head moves, in order to maintain fixation when moving, does not need visual input.
What is Optokinetic (OKN) Nystagmus?
Optokinetic nystagmus - non-pathological behaviour, it is when making very large head turns or for example looking out a train, relies on both smooth pursuit movement and saccades. The smooth part is characterised by slow-phase velocity.
Findings of Costa (2011) on Down syndrome patients and OKN Nystagmus?
The DS patients had increased number and amplitude of intruding saccades during smooth pursuit movement.
May help understand why DS people struggle with everyday tasks - e.g. reading may affect intellectual capacity.
What interaction may eye-movements have on visual field loss i.e. after neurovascular incident. Study?
May help compensate.
What real-world functions do eye-movements have?
Locate objects
Direct actions towards those objects
Guide actions upon those objects
Check the status of actions
What type of scales does the human perceptual system use?
Lagarithmic scales
An example of the human perceptual system using logarithmic scales?
Small weight changes are easier to detect in lighter weights than heavier weights - Fechners law
6 extraoccular muscles?
Superior Rectus, Lateral Rectus, Inferior rectus, medial rectus
Superior oblique, inferior oblique
Nervous supply to the extraoccular muscles?
Lateral Rectus (VI), Superior Oblique (IV), Superior rectus (III) Inferior rectus (III) Medial rectus (III) Inferior oblique (III)
What movement does each muscle of the eye cause?
Superior rectus - Elevation and intorsion
Inferior rectus - depression and extorsion
Lateral rectus - abduction
Medial rectus - adduction
Inferior oblique - elevation extorsion
Superior oblique - depression intorsion
What are the two systems in the human perceptual system?
System I - Fast gut reactions (sensorimotor system - online cognition)
System II - Slow, rational (offline cognition)
What is the cognitive action interaction theory?
That ‘higher-order cognition’ should be considered as:
(i) a somewhat separate system that interacts with the ‘sensorimotor control system’;
(ii) a system that is underpinned by the sensorimotor control system.
What is the Weber-Fechner law?
The law that the perceived change in stimuli is proportional to the magnitude initial stimuli, Fechners law includes a measure of subjectivity (varies from person to person).
Information theory formula?
Who came up with it?
H = -ξ p(x) log2 p(x)
p(x) = probability of x
H = information entropy
log2 p(x) = information
Information = log2 1/p
p = number of possible events
Claude Shannon
Given that information is log2 1/p, how would you work out the amount of information given in a coin toss (expressed as ‘bits’)?
log2 1/0.5 = 1 bit
because the chance of heads/tails is 0.5 each
What has Friston suggested recently in terms of information theory?
That a unified brain theory could help us understand how the brain uses information to help minimise surprise.
What is DCD and what test is used in diagnosis?
Developmental discoordination disorder - CKAT
Deficits in the acquisition and automation of motor processes.
What is bayes rule?
A rule that can be used to determine the probability of something occurring.
The posterior probability that the child has DCD given a positive test is the likelihood probability of a positive test when the child has DCD times the prior probability of a child with DCD divided by the marginal probability that it’s a positive test
𝑝 𝐷𝐶𝐷 + 𝑡𝑒𝑠𝑡) =
𝑝 +𝑡𝑒𝑠𝑡 𝐷𝐶𝐷 𝑝(𝐷𝐶𝐷)
————————
𝑝(+𝑡𝑒𝑠𝑡)
Why is Bayes theory important?
Can allow us to determine probability of someone having a condition
The brain may use bayesian mechanics in functioning ‘bayesian brain hypothesis’ - why humans make decisions
An account of why humans learn to survive in uncertain environments
What is the classical theory about system I and II (old theory) ?
Embodied cognition (EC) thesis holds that the nature of the human mind is largely determined by the form of the human body. EC philosophers and psychologists argue that all aspects of cognition are shaped by aspects of the body
Evidence for The combined action interaction theory?
WM tasks are better when a preferred hand is used - system I and II are interacting
What is perception?
The decoding (and then encoding) about the world (which includes us) within any given modality.
What human perceptual system exploits chemical energy?
The olfactory system
The integumentary system - e.g. noxious substance on the skin
Taste receptors
What perceptual system exploits thermal energy?
Integumentary system - thermal receptors
What perceptual system exploits kinetic energy?
Touch receptors in the integumentary system
What is it about vision that allows us to be evolutionarily successful?
Lots of information - can hunt prey/avoid predators
What’s the Cambrian explosion?
A huge large number of different organisms, most plausible is that vision sparked it, as vision provided organisms with information about the environment
What is unique about colour information?
Can start to tell apart different organisms from each other - things to eat, predators e.t.c.
Why is the fact that physical laws of the universe were discovered by isaac newton important?
If everything obeys laws we can then make inferences about the external world leading to perception of the world using different modalities
What contributions did James Clark Maxwell make to scieince
Formulated the theory unifying electricity and magnetism - electromagnetism.
Who was Herman Helmoltz? His contribution to psychology.
He was a scientist that laid the fundaments of visual science. The light that reaches the retina is ambiguous - we use top down processing to produce an estimate of the information (top down information is information that has already been stored e.g. what a lion looks like.
What didi JJ Gibson contribute to psychology?
The ecological school of psychology. That visual perception interacts with the world. What is logically true is not necessarily ecologically true, the human perceptual system integrally relies on the environment.
- Turned out to be incomplete
What do modern accepted theories of visual perception suggest about top-down/bottom-up processing?
They are both important, we use both - Daniel Wolpert suggested that humans use bayesian principles to make predictions and guide our actions.
