Sensation and Perception 1 Flashcards
What is the absolute threshold?
the smallest quantity of a stimulus that a person can detect
e.g. the smallest amount of light needed for someone to see the light
What’s a difference threshold? What’s jnd?
The smallest amount of change in an input that can be detected
When a stimulus changes by this minimal amount, this is called the jnd (just noticeable difference)
What is Weber’s law? What is it used for?
Proportional change
e.g. humans can tell the difference between a backpack that weighs 25 pounds and 25.5 pounds. Less likely to notice the difference between a 50 pound backpack and a 50.5 pound backpack.
Weber’s law allows us to compare the sensitivity of different sensory modalities
What is the decision criteria? What is a liberal and conservative criterion?
e.g. Matt didn’t hear what someone said but will suggest he heard it anyways - liberal criteria
e.g. Fiona didn’t hear what someone says and will admit to that - conservative criteria
Maybe this doesn’t reflect their hearing but how they handle uncertainty
An organism’s rule for how much evidence is needed before responding
Liberal: high false alarms, high hits, no misses
Conservative: low hits, low false alarm, many misses
What is signal detection theory?
The detection of a stimulus depends on both the intensity of the stimulus and the physical/psychological state of an individual
What is transduction?
the process where a physical stimulus is converted into a signal within the nervous system
requires the conversion of different types of energy into information that our brains can make sense of
What is sensation?
The process of interpreting the world around us
What is perception?
Involves the aggregation and interpretation of sensory input from raw neural signals into meaningful information
What are the senses?
Visual
Auditory
Smell (olfaction)
Taste (gustatory)
Skin sensations (somatosensation)
How do we receive sensations into our brain?
Neurons communicate with other neurons through electrical signals
Each neuron is connected to 10,000 other neurons
This allows for rapid and efficient communication within the brain, and from the brain to the rest of the body.
Each pulse is at a fixed speed and intensity, one pulse can’t move faster or more intensely than the previous one
What is anatomical coding?
When a given area is stimulated
e.g. pressure is applied to your arm
Nerves from this area inform the brain as to which area of the body is being stimulated
What is temporal coding?
The rate at which neurons fire can deviate, depending on the intensity of the stimulus
e.g. extreme pain would elicit more pulses per second than moderate pain
What are the 6 layers of the cerebral cortex?
Layer 1: Glial cells and axons which run parallel to the pial surface. Interconnections with cortex area. Very few cellular bodies
Layer 2: small pyramidal cells that project to the other cortical areas
Layer 3: stellate cells. receive the most afferent signals from the thalamus
Layer 4: Big pyramidal cells, origins of the descending pathways towards the spinal cord
Layer 5: Neurons that project to the thalamus
What is the visual spectrum? Where are humans on this spectrum?
Vision is stimulated by light energy, low frequency and high frequency
High frequency: more energy, shorter wavelength e.g. gamma rays
Low frequency: less energy, longer wavelength e.g. radio
Spectrum: gamma, x ray, ultraviolet, infrared, microwave, radio
Humans can see a small amount of this spectrum, between ultraviolet and infrared
What are ganglion cells, rods and cones?
Ganglion cells: circadian rhythms and pupillary reflex, 3 million cells in humans
Rods: black and white, 120 million cells in humans, located on outer regions of retina, low visual acuity, respond to lower light intensities
Cones: colours, 6 million cells in humans, high visual acuity, respond greater to light intensities
How does our visual field work?
Left hemisphere perceives our right visual field
Right hemisphere [receives our left visual field
Lateral Geniculate Nuclei (thalamus)
Optic tract
Optic chiasma
Optic nerve
Temporal Retina
Nasal Retina
What is the fovea?
Located at the back of the eye
Vision is the sharpest here
What is a blind spot?
Where cells from the eye connect to the optic nerve
We can’t see anything that falls on that part of the retina
What is the cornea, iris, pupil, lens and retina?
Cornea: outside surface of the eye, bends light that enters the eye
Iris: bands of muscle that contract and relax to regulate how much light enters the eye via the pupil
Pupil: opening into the eye, controlled by the iris
Lens: adjust focus on near or far objects
Retina: photoreceptor cells that are stimulated by different qualities of light
What is a distal and proximal stimulus?
Proximal: the stimulus as it appears to the sensory receptors
Distal: actual 3D objects in the world
What is Myopia? What are the causes?
Short sightedness
The eyeball ‘stretches’
Images are no longer projected to the retina but just in front of it
Causes: near work hypothesis (working too closely to computers) and visual stimuli hypothesis (a lack of normal visual stimulation, which impairs optic development)
How do coloured photopigments work?
Cones contain photopigments that are broken down by certain frequencies of light
Some cones respond to red light, while others respond to green and others blue
Certain objects reflect different wavelengths of light, this is how we perceive objects of different colours
How do black and white photopigments work?
Rods contain Rhodopsin
This is a photopigment that breaks down more readily in response to light
Allows us to distinguish between light and dark stimuli
Rods are numerous in the periphery of the eye so we are essentially colour blind to objects in the peripheral of our vision
What is brightness contrast?
e.g. small grey square surrounded by white, or black or darker grey.
smaller grey squares are all the same brightness but appear to become brighter as the surrounding background darkens
What is the opponent process theory of colour?
3 types of cones: red, blue and green
e.g. Excitation of blue cone means that red and green cones won’t become activated
When the blue is no longer activated, then green and red will spring suddenly into action
What is hue?
Distinguishes different colours from one another
Colours can vary in brightness but share the same hue
What is brightness?
Differentiates how far colour is from black (low brightness) and white (high brightness)
Brightness is a property processed by both achromatic colours e.g. colour that have no hue e.g. black, white, grey) as well as chromatic colours (e.g. colours that have hue, red, blue, yellow)
What is synaesthesia?
Involves a fusion of different senses and inputs
e.g.
Grapheme colour synaesthesia
where letters and numbers are associated with different colours
What is saturation?
refers to the purity of colour
e.g. colours that are more achromatic are less saturated (less pure) than colours that have less achromatic colour
achromatic colour e.g. black, white, grey, neutral colours
What is the rubber hand paradigm?
real hand and rubber hand
rubber hand replaced our other hand
paint brush is brushing along the rubber hand and real hand
we can feel this sensation on ‘both’ hands
as we are feeling it and seeing it
