Sensation and Perception Flashcards
modalities
sensory brain region that process different components of the perceptual world.
define psychophysics
scientific method for investigation of relationships between physical stimuli and psychological experience
what is the absolute threshold
the minimum stimulus discriminated reliably from no stimulus. need to respond yes 50% of the time for a trial to be successful
what are the 5 senses thresholds
on picture
what is the difference threshold / just noticeable difference
the minimum difference in stimulus intensity necessary to tell the two apart
what is webers law
that the just noticeable difference is a constant proportion despite variations in the stimulus
what is the aim in detection experiments
for the ppt to discriminate the presence of a stimulus from background noise
how does a ppt do this
adopt a response criterion (= attitude to the decision)
what is signal detection theory
an observation that the response to stimulus depends on a persons sensitivity to the stimulus in the presence of noise and on a persons response criterion
Signal detection theory allows us to measure sensitivity and bias separately how?
using hits and false alarms.
describe the ways in which a ppts response could be categorised
hit = said yes was yes
miss = said no but was there
false alarm = said yes wasnt there
correct rejection = was no said no
what effects response criterion
your evaluation of the costs and benefits of the different possible outcomes e.g is there a tumour said no but it is there = death
what is d prime
a statistic that gives a relatively pure measure of the observers sensitivity or ability to detect signals
what is sensory adaptation
sensitivity to prolonged stimulation tends to decline over time as an organism adapts to current conditions
what is visual acuity
ability to see fine detail
what is visible light
the portion of the electromagnetic spectrum that can be seen
how we see
see picture
describe the retina
the surface of the retina is composed of photoreceptor cells the rods and cone beneath a layer of transparent neurons the bipolar and retinal ganglion cells
describe the world on your retina
inverted as has passed through the lens
topographic - reflects real world spatial relationships
much of view common to both retina but also sees parts the other doesnt
what happens from the retina to the brain
visual signals relay to primary visual cortex (V1) via the lateral geniculate nucleus
prior to this half the optic nerve fibres from either eye cross over at the optic chiasm so Right visual field to left hemisphere
what is a receptive field
region of the sensory surface that when stimulated causes a change in firing rate of thay neuron - on centre cells off center cells
receptive field info
each photoreceptor receives light from a specific part of the visual field so its receptive field corresponds to a specific part of the visual field
what is the receptive field of the ganglion determined by
the positions of the photoreceptors to which it connects
describe the parts of the receptive fields
functional and spatial characteristics - most are center surround type. ganglion cell is sensitive to differences between illumination in the centre and surround portions of its receptive field
describe simple cells
larger receptive fields than ganglion cells they respond to edges of a certain orientation in a certain position
describe complex cells
combine input from many simple cells with the same orientation turning and adjacent receptive fields. can respond to an edge of a particular orientatopn st any position in their receptive field
describe hypercomplex cells
combine input from many complex cells to respond to increasingly refined features
bottom up hierarchy of feature detectors see phone
see picture
what is motion
a powerful cue for alerting and orientating and for form perception
what is space constancy
we factor out self generated movement to perceive only movement arising in the world
what are the two possibilities for space constancy
monitoring eye muscle systems for sensory (afferent) or motor (efferent) signals
observations linked to space constancy
the world does not stay stable when the eye is moved passively (sensory signal but no motor signal = space constancy fails)
the world seems to move when we try to move a paralysed eye (motor signal but no sensory signal = space constancy maintained)