sensation and perception 1 Flashcards
what is sensation
process of interpreting the world around us
requires transduction
what is transduction
process of converting different types of energy into information that our brains can make sense of
what is perception
involves aggregation and interpretation of sensory input from raw neural signals into meaningful information
what main 5 senses do we have, and what are the fancy names for them
sight (vision
hearing (audition)
smell (olfaction)
taste (gustation)
skin sensations (somatosensation)
sensory coding - anatomical coding
when area is stimulated, nerves from this area inform the brain as to which area of the body is being stimulated
sensory coding - temporal coding
the rate at which neurons fire can deviate, depending on the intensity of the stimulus
for example, extreme pain would elicit more pulses per second than moderate pain
the neocortex is only present in mammals, and is divided into 6 layers - what are these layers
1) glial cells and axons run parallel to pial surface
2) 3) small pyramidal cells that project to other cortical brain areas
4) stellate cells. receive most afferent signals from the thalamus
5) big pyramidal cell, origins of the descending pathways towards the spinal cord
6) neurons that project to the thalamus
vision is affected by light energy, which can have different frequencies
light on EM spectrum, from high frequency/short wavelength to low frequency/longer wavelength
gamma ray
x ray
ultraviolet
visible
infrared
microwave
radiowave
what are the functions of ganglion cells
circadian rhythms and pupillary reflex
what are the functions of cone and rod cells
rods = black and white, very sensitive 120, million cells, useful for night vision, low visual acuity
cones = colours, 6 million cells, high visual acuity
what is the fovea in the eye
located at the back of the eye, and is where our vision is sharpest
what is the blind spot
where cells from the eye connect to the optic nerve, and so we cannot see anything that falls on that part of the retina
what is the cornea
outside of the surface of the eye, bends the light that enters the eye
what is the iris
bands of muscle that contract and relax to regulate how much light enters the eye via the pupil
what is the pupil
the opening into the eye, controlled by the iris
what is the lens
can be adjusted to focus on near or far object
what is the retina
contains photoreceptor cells that are stimulated by different quantities of light
what is the proximal and distal stimulus
proximal = stimulus as it appears to the sensory receptors
distal stimulus = actual 3D object out in the world
visual deficits - myopia
short sightedness
eyeball stretches, such that images are no longer projected onto the retina, but instead, just in front of it
colour vision - what are photopigments
cones contain photopigments that are broken down by certain frequencies of ligh
certain cones repos to red light, while others respond to blue or green light
certain objects reflect different wavelengths of light - this is how we perceive objects of different colours
how to we distinguish between light and dark stimuli?
rods contain rhodopsin, which is a photopigment that breaks down more readily in response to light - this allows us to distinguish between light and dark stimuli
why are we essentially colour blind to objects in our peripheral vision?
rods are more numerous in the periphery of the eye
what is the opponent process theory of colour
the theory that we have there cone types (red, green and blue) which inhibit each other when excited
shows how afterimages work - prolonged excitation of red receptors means that as soon as these receptors are no longer activated the blue and green receptors suddenly spring into action
what is hue
distinguishes different colours from one another
colours that can vary in brightness, but share the same hue
what is brightness
differentiates how far a colour is from black or white
what is saturation
refers to the purity of a colour
what is synaesthesia
involves a fusion of different senses and input
e.g., letters and numbers associated with different colours (grapheme colour synaesthesia)
e.g., different sounds trigger the sensation of seeing colours (chromaesthesia)
e.g., different sounds trigger tactile sensations in parts of the body (auditory tactile synaesthesia)
what is a just noticeable difference
smallest change in something that can be noticed
the smallest difference an organism can reliably detect between two stimuli
what is Weber’s law
smallest noticeable change in a stimulus is a constant ratio of the original stimulus
e.g., object weighs 2kg in right hand and 2.2kg in left, you may notice a difference, but if object in right hand was 5kg the object in left hand would need to be more than 5.2kg
what is signal detection theory
a way to measure how well people can process information in the presence of distraction
involves the measurement of the difference between two distinct patterns
sensitivity vs decision criteria - low and high sensitivity
lower sensitivity - awill always have some false alarms and misses. overlapping signals for two categories
higher sensitivity - avoid misses and false alarms, signals from categories do not overlap much
sensitivity vs decision criteria: liberal vs conservative criterion
liberal: high false alarms, high hits, no misses
conservative: low hits, low false alarms, many misses
