Lecture 3 - Perception Flashcards
What is perception?
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.
How is human perception different?
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.
Give an example of this difference
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.
Why is it hard for computers to copy human perception?
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.
What are the two approaches to understanding perception?
Direct perception theories and constructive perception theories
Describe direct perception theories
Bottom-up processing.
Perception comes from stimuli in the environment.
Parts are identified and put together, and then recognition occurs.
Describe constructive perception theories.
Top-down processing.
Processing originates in the brain, “top” of the perceptual system.
People actively construct perceptions using information based on expectations.
What is top down processing?
Processing starts in the brain
Person’s knowledge, experience, and expectations.
What is bottom up processing?
Perception starts with the senses
Incoming raw data
Energy registering on receptors.
Is the perception of pain top down or bottom up?
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.
How is top down processing used in language?
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.
What is Helmholtz’s unconscious inference?
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.
What is Gesalt’s principle of perceptual organisation?
The mind groups patterns according to intrinsic laws of perceptual organization based on knowledge about the world.
What is the figure ground principle?
There needs to be a distinction between an object and its background
What is the principle of good continuation?
Lines tend to be seen as following the smoothest path
Good continuation helps us perceive the rope as a single strand.