perception Flashcards
what is a pure tone made up of
amplitude (maximum air pressure in each cycle)
frequency (the number of cycles of changing air pressure per second)
amplitude and loudness
there is positive correlation between increased amplitude and perceived loudness (this does not increase 1-1)
auditory transduction
- basilar membrane in the cochlea responds to frequencies
- the membrane is ordered so that the base responds to high frequencies and the apex responds to low frequencies
- it is made up of hair cells which fire based on frequency
basilar membrane hair cells
mechanoreceptors which send electrical signals to the brain via the auditory nerve
place coding (auditory)
determining the amplitude of sound frequencies depending on which hair cells are activated
what is the human hearing range
20-20,000 Hz
complex sounds
sounds with a mix of different frequencies
the fundamental frequency
the lowest frequency of the complex sound
harmonic complex sounds
all frequencies are integer multiples of the least common denominator
auditory masking
using a sound with the intention of covering up human detection of another sound
visual vestibular integration dysfunction
visual cues indicate that you are rotating, but vestibular information contradicts this
the compromise feels like falling
e.g. camera obscura tunnel
pseudophone
creates discrepancies between where the brain locates a sound and where it visually is
what is flavour integration comprised of (4)
olfactory receptors in nose
light receptors in eyes (colour changes perception)
touch receptors in mouth (crunchiness)
sound receptors in ears (hearing texture influences perception)
visual acuity
ability to see fine detail
what is the process of an image passing through to the primary visual cortex?
LIGHT -> RETINA [photosensitive ganglion cells] -> OPTIC NERVE AXONS -> OPTIC CHIASM [cross over] -> LATERAL GENICULATE NUCLEUS -> PRIMARY VISUAL CORTEX
why does v1 receive a distorted image
the fovea is over represented in terms of photoreceptors, so central vision is much more detailed
what is the retina made up of
2
120 mil photoreceptors that respond to light
fovea - responsible for visual acuity (focuses on objects of interest)
what do rods/cones detect
cones = colour, make up the fovea rods = low light, make up majority of photoreceptors
how does the visual system interpret upside down images
it has a topographic map system, so that size and dimensions are preserved
two streams of the primary visual cortex
dorsal - to superior parietal lobe; ‘where’ system
ventral - to inferior temporal lobe; ‘what’ system
specialised areas to process visual stimuli (3)
FFA Fusiform Face area - faces
PPA Parahippocampal Place area - places
EBA Extrastriate Body Area - bodies
two visual systems in a frog
lesions to visual area created blind area
would ignore prey in blind spot, but would still manage to jump around obstacles in blind spot
evidence for distinct dorsal stream
ppts with optic ataxia = dorsal damage
- no difficulty identifying stimuli, but difficulty moving towards targets / pointing without delay
evidence for distinct ventral stream
ppts with visual agnosia = ventral damage
- highly proficient at grasping objects, but incapable of facial recognition or copying pictures in drawing (but not from memory)
size estimation & ebbinghaus illustration
2 circles of the same size
perceive the circle surrounded by smaller circles as bigger, because we use surrounding stimuli and information to help estimate
change blindness
shows that there are gaps in our perceptual systems and we may discard details that do not make logical sense
space based theory of attention
‘spotlight’ metaphor
we move our attention across a space, we then focus on whatever falls within that visual field
‘zoom lens’ metaphor
the attention area can grow or shrink depending on what is being processed
3 types of visual searches (space based theory of attention)
feature search - target is defined by a single feature (EX colour)
conjunction search - target is defined by the conjunction of two+ features
spatial configuration search - the target and the distractors contain the same basic features
the binding problem - visual attention
the challenge of combining different visual features, as colour motion and orientation are represented by separate neurons
object based theory of attention
feature integration;
a set of basic features can be processes preattentively, but the correct binding of features to objects requires attention
evidence that visual features are represented separately and need to be bound together
illusory conjunction - the incorrect combining of the features of two objects into one object (EX seeing a green square and red circle, but processing it as a green circle)
saliency - bottom-up attention
processing noticeable edges, colour, brightness
used in experimental settings, but in real life salient information may not be salient and vice versa // ppl tend to have fixations on nature which isnt always salient
top-down attention
fixating on useful information, or contextual cues which may be complex
yarbus & the unexpected visitor (top-down attention)
ppts asked to examine a painting, with different objectives
the gaze behaviour changed dramatically depending on what the goal was
