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
