Perception Argumentative – Flashcards

– Emphasizes the stimulus characteristics that are important when you recognize an object
– Specifically, it is the process by which the physical stimuli from the environment are registered on the sensory receptors and then passed on to higher, more sophisticated levels of the perceptual system

– Distal is the actual stimulus
– Proximal is how your system perceives it

– AKA Iconic memory (visual sensory memory)
– preserves an image of a visual stimulus for a brief period of time after the stimulus has disappeared

– Visual information registered on retina
– Proximal stimulus makes its way through the Visual Pathway to the Primary Visual Cortex

– Gestalt Psychology
Emphasizes that humans have basic tendencies to actively organize what they see
Also stresses that for perception, the WHOLE IS GREATER THAN THE SUM OF ITS PARTS
– A Gestalt: Has an overall quality that transcends the individual elements

– When two areas share a common boundary…
– Figure: Clearly defined edges
– Ground: Leftover
– These are not always fixed, such as in an Ambiguous Figure-Ground Relationship

– Bottom-up: the neurons in the visual cortex become adapted to one figure, so you are more likely to see the alternative (habituation makes you end up switching)
– Top-down: people actively try to solve the visual paradox by switching between the two reasonable solutions (“I want to look at the…)

– We can even see the figure-ground relationship when a scene has no clear-cut boundary between the figure and the ground
– One type of illusion related to this is Illusory Contours

– 1. Template Theory
– 2. Feature-Analysis Theory
– 3. Recognition-by-Components Theory

– An early theory of object recognition
– Have a series of templates stored in memory
– Visual system matches what it perceives with the stored templates for recognition

– Relatively flexible approach to object recognition
– Assume a visual stimulus is composed of a small number of characteristics or components called Distinctive Features
1. When looking at a stimulus, your visual system notes the presence or absence of these Distinctive Features
2. Then compares them to a list in memory
3. Then comes up with the object you are looking at

– These models do a good job explaining how we perceive a wide variety of 2D patterns
– Consistent with research and evidence from neuroscience

Problems:
1. Theories were constructed to explain simple recognition (symbols)
2. Shapes that occur in nature are much more complex
3. Recognizing natural objects have far too many distinctive features

– Developed by Irving Biederman to explain 3D shape recognition
– Basic assumption is that a specific view of an object can be represented as an arrangement of simple 3-D shapes called geons
– fMRI research confirms this
– But based on recent research, this theory requires modification…

The Viewer-Centered approach is that modification
– This approach proposes we store a small number of views of 3D objects, rather than just one view

– Overall, both feature-analysis and recognition-by-components can explain some portion of our remarkable skill in recognizing objects
– But this area of research is still under investigation…
– For e.g., a scene with multiple complex objects, what processes are involved then?

– Contextual factors and their related expectations can affect speed of object recognition
– Example of top-down processing: How a person’s concepts/expectations/memory can influence object recognition
– Especially strong when stimulus is registered for just a fraction of a second and when stimuli are incomplete or ambiguous
– Bottom-up and top-down processing are necessary to explain the complexities of object recognition

– Size Constancy: We tend to perceive objects as remaining the same size even when they move to different distances
– AKA Perception of the size of an object does not depend solely on the size of the object’s image on the receptors

– Would we perceive a scent to be stronger if we took a big sniff compared to a little sniff? NO!
– This is because big sniff = more molecules = yet you EXPECTED MORE MOLECULES

– Reading requires factors other than just letters and words
e.g., we can still read the boy cuold not slove the porblme
– Word-Superiority effect: We can identify a single letter more accurately and more rapidly when it appears in a meaningful word than when it appears alone by itself or else in a meaningless string of unrelated letters
e.g., plan vs. pnla
‘plan’ is seen as 1 unit vs. ‘pnla’ is seen as 4 units

– Word-in-a-sentence Effect: Word recognized quicker when it is presented in a meaningful sentence than if it is part of a jumbled sentence or in isolation
– “Mary drank her orange JUICE” vs. “Mary JUICE her orange drank” vs. “JUICE”
Research…
Depending what the word “bea_s” was in, the person would top-down the word and that would influence whether it would become “bears” or “beans”

Context can dramatically influence reading speed
– Previous letters in a word help identify remaining letters more quickly
– Other words in a sentence help you identify the individual words more quickly
– Top-down processing is extremely important when reading sloppy hand-written notes

– Sometimes we overuse top-down processing strategies and make a “smart-mistake”
– Two such smart mistakes are
1. Change Blindness
2. Inattentional Blindness

– Stranger-and-the-door Study
Happens because when perceiving an entire scene, our top-down processing encourages us to assume that the basic meaning of the scene will remain stable

Highlights the fact that changes that change the actual meaning of the scene are perceived much more readily than those that do not

– When are you paying attention to something, sometimes you fail to notice an unexpected but completely visible object
– People are more likely to demonstrate inattentional blindness when the primary task is cognitively demanding (guerilla costume and basketball)

– Often, our cognitive processes are remarkably efficient and accurate.
Smart-Mistakes like Inattentional Blindess and Change Blindess have low Ecological Validity, meaning they aren’t very applicable in real-life situations.

– Theory of Unconscious Inference: Some of our perceptions are the result of unconscious assumptions that we make about the environment
– Includes the Likelihood Principle: States we perceive the object that is most likely to have caused the pattern of stimuli we have received

– Gestalt psychologists were concerned with perceptual organization
AKA the way elements are grouped together to create larger objects

– Proposed a number of laws of perceptual organization…
1. Law of Good Continuation
2. Law of Pragnanz (good figure/simplicity)
3. Law of Similarity
4. Law of Familiarity

– Points that should follow, bla bla into one full string

– AKA Law of Good Figure or Law of Simplicity
– States that every stimulus pattern is seen in such a way as the resulting structure is as simple as possible

– Similar things tend to be grouped together

– Things that form patterns that are familiar or meaningful are likely to be grouped together

– Gestalt laws aren’t actually laws; they are heuristics
– Can contrast with algorithms (trying out every possible option)

– Overall, we recognize faces on a holistic basis
– AKA, we perceive faces in terms of its gestalt
– FP mostly takes place in Inferotemporal cortex and fusiform gyrus
– Evidence shows that animals also have facial perception
– Gestalt properties of FP highlighted in work on the face-inversion effect
Brain responds quickly to up-right faces
Matches behavioural research

– Applied research focuses on people’s real-life ability to recognize faces

– “refers to the systematic variation in the way that groups of people perform on the same cognitive task”
– Ind. Diff. with schizo: difficulty perceiving faces and facial expressions

– During SP, your auditory system must record the sound vibrations generated by someone talking; then the system must translate these vibrations into a sequence of sounds you perceive as speech
– SP is extremely complex…
1. Characteristics of SP
2. Theories of SP

– Phoneme (basic unit of spoken language about 90)
Important characteristics of SP…
1. Listeners can impose boundaries between words, even when these words are not separated by silence
2. Phoneme pronunciation varies tremendously
3. Context allows listeners to fill in some of the missing sounds
4. Visual cues from the speaker’s mouth helps us interpret ambiguous sounds

Note: word boundaries – such as a pause – happen less than 40% of time

Phoneme perception is difficult for these reasons…
1. Speakers’ voices vary tremendously in pitch and tone, as well as speed
2. Speakers fail to produce phonemes in a precise fashion
3. Coarticulation: when speaking, your mouth remains in somewhat the same shape as it was when you pronounced your PREVIOUS phoneme, in addition, your mouth is prepare to produce the NEXT phoneme

– People are active listeners: instead of just passively receiving speech sounds, we top-down as a cue to figure out speech
– Top-down SP uses Phonemic Restoration: People fill in a missing phoneme using contextual meaning as a cue
Research… (Phonemic Restoration)
“It was found that the wh*eel was on the axle”
“It was found that the h*eel was on the shoe”
“it was found that the p”eel was on the orange”

– Information from a speaker’s lips and face helps to resolve ambiguities from the speech signal(integrate visual cues with auditory cues during SP)
– Illustrated by the McGurk Effect (audio+visual = hybrid word)
Refer to the influence of visual information on SP, when individuals must integrate both visual and auditory information

Note: Superior Temporal Sulcus gives rise to the McGurk Effect

1. Specific Mechanism Approach
– AKA Speech-is-Special Approach
– Humans are born with a specialized device that allows us to decode speech stimuli
– Supporters argue humans posses a phonetic module (speech module)
Results from categorical perception tasks were thought to favour the phonetic module

2. General Mechanism Approach
– Argues we can explain SP without proposing any phonetic module
– Instead humans use the same neural mechanisms to process both speech sounds and non-speech sounds
– Thus, speech perception is a learned ability
– Current research favours this approach
(people slowly develop into “phoneme recognizing machines”!)