Week 10 Flashcards
perceptual failures
cases in which our perceptual experience of a stimulus differs form the actual characteristics of that stimulus
three approaches to perception
computational model
constructivist approach
ecological approach
computational model
focuses on how computations by the nervous system translate raw sensory stimulation into an experience of reality
Owes much to the other two theories that came earlier
constructivist approach
taken by those who argue that the perceptual system uses fragments of sensory information to construct an image of reality
same stimulus creates different perceptions in different people
Our perception is strongly influenced by what we have learned from our experiences and by the expectations and inferences that those experiences create
ecological approach
an approach to perception maintaining that humans and other species are so well adapted to their natural environment that many aspects of the world are perceived without requiring higher-level analysis and inferences
Gibson
Primary goal of perception is to support actions by ‘tuning in’ to the part of the environment that is most important for performing those actions
Less interested in our inferences
perceptual organisation
task of determining what edges and other stimuli go together to form an object
creates subjective contours
figure ground discrimination
ability to organise a visual scene so that it contains meaningful figures set against a less relevant ground
reversibility figures
you can repeatedly reverse your perceptual organisation of what is figure and what is ground
Gestalt grouping principles
proximity similarity continuity closure closure texture simplicity common fate
common fate
when objects are moving in the same direction at the same speed, we tend to perceive them as being together
Palmer’s three additional grouping principles
synchrony
common region
connectedness
visual dominance
if conflicting impressions, believe our eyes rather than ears
depth perception
the ability to perceive distance
depth perception elements
interposition or occlusion relative size height in visual field linear perspective reduced clarity light and shadow gradient of texture
interposition or occlusion
closer objects block the view of things farther away
relative size
if two objects are assumed to be about the same size, the object producing a larger image on the retina is perceived to be closer than the one producing a smaller image
height in the visual field
On the ground, more distant objects are usually higher in the visual field than those nearby
linear perspective
objects closer to the point at which two lines appear to converge are perceived as being at a greater distance
reduced clarity
increased distance usually produces less clarity and a blue hue
light and shadow
perception of 3D
gradient of texture
graduated change in the texture, or grain, of the visual field whereby objects with finer, less detailed textures are perceived as more distant
motion parallax
Difference in the apparent rate of movement of different objects provides information about the relative distance of those objects
Muscles surrounding the lens either tights, to make the lens more curved for focusing on close objects, or relax to flatten the lens for focusing on distant objects
Information relayed to the brain, providing an ocular accomodation that helps create the perception of an object’s distance
eye convergence
rotation of the eyes inwards to project the image of an object on each retina
closer the object, more the eyes must converge
retinal disparity
a depth cue based on the difference between two retinal images of the world
optical flow
changes in retinal images across the entire visual field
looming
a motion cue involving a rapid expansion in the size of an image so that it fills the retina
stroboscopic illusion
illusion of motion that is created when we see slightly different images or slightly displaced lights flashed in rapid succession
perceptual constancy
The perception of objects as constant in shape, size, colour and other properties despite changes in their retinal image
bottom up processing
Stimulus is first analysed into basic features before processing in brain
feature detectors
top down processing
People use their knowledge in making inferences to recognise objects, words or melodies, especially when sensory information is vague or ambiguous
In hearing, allows to compensate for ambiguous stimuli
Also involved in pareidolia: perception of a specific image in an ambiguous stimulus array
object superiority
detecting a feature faster when embedded in a pattern resembling a 3D object than when it appeared within a random pattern of lines
word superiority effect
when strings of letters are briefly flashed on a screen, people’s ability to detect target letters is better if the string forms a word than if it is a non word
PDP
theoretical model of object recognition in which various elements of the objects are thought to be simultaneously analysed by several widely distributed but connected neural units in the brain
3 characteristics of attention
Improves mental processing
Takes effort
Attentional resources are limited
overt orientation
shifting attention that involves pointing sensory systems at a particular stimulus
covert orientation
not pointing systems at stimulus so obviously; I.e. not moving head around to hear a conversation
inattentional blindness
ignoring stimuli occurring in other parts to what you’re focusing on
motion parallax
motion produced cue that describes the tendency when moving forwards rapidly to perceive differential speed sin the objects passing by
deletion
gradual occlusion of a moving object as it passes behind another object.
accretion
gradual reappearance of a moving object as it emerges from behind another object.
binocular depth cues
disparity or difference between the retinal images
zipper effect
ability of our mind to seamlessly merge two images together
pure tones
high pitched flute notes and tuning forks; created by a single sine wave; can be of any specific amplitude or frequency
loudness
Loudness measured by dB
frequency
number of cycles within a given time period
Frequency measure in Hz, where 1Hz is one cycle per second
High frequency sound waves are high pitched
Low frequency waves are low pitched
Audible range of sound frequencies: 20-20,000 Hz; greatest sensitivity to frequencies in the middle
timbre
all the other perceptual aspects of a sound besides loudness, pitch and duration
human ear 3 sections
pinna
middle ear
inner ear
pinna
visible part of the ear that protrudes from our heads, the auditory canal and the tympanic membrane or eardrum
middle ear
three bones called ossicles which are names the malleus (hammer), incus (anvil) and staples (stirrup)
inner ear
semi circular canals which are involved in balance and movement (the vestibular sense) and the cochlea. Cochlea is a fluid filled, snail-shaped structure that contains the sensory receptor cells of the auditory system
auditory scene analysis
process by which sound sources in the auditory scene are separated into belonging to individual perceptions/streams
common heurestics of auditory scene analysis
Onset time: sounds that start at different times are likely to come from different sources.
Location: a single sound source tends to come from one location and to move continuously
Similarity of timbre and pitch: similar sounds are grouped together
Proximity in time: sounds that occur in rapid succession usually come form the same source
Auditory continuity: sounds that stay constant or change smoothly are usually from the same source
hit
stimulus present (signal and noise) response present
false alarm
stimulus absent (noise only) response present
miss
stimulus present (signal and noise) response absent
correct rejection
stimulus absent (noise only) response absent
parallel processing
our ability to search for targets rapidly and automatically
binaural cues
interaural level differences
interaural timing differences
