Chapter 2: Sensation and Perception Flashcards
What is sensation?
Conversion of “raw” signal of physical, electromagnetic, auditory, and other information from our internal and external environment to electrical signals in the nervous system. Performed by receptors in the PNS and info is sent to CNS in the form of action potentials.
What is perception?
Processing of incoming signal to make sense of its significance
What are sensory receptors? List 7 examples.
Neurons that respond to stimuli and trigger electrical signals. They transmit data to the CNS through sensory ganglia (neuronal cell bodies outside CNS) then to projection areas in the brain.
Ex. Photoreceptors, Hair cells, Nocireceptors, Thermoreceptors, Osmoreceptors, Olfactory Receptors, Taste Receptors
What is a threshold? List the three types.
A threshold is the minimum amount of a stimulus that renders a difference in perception. The 3 types are absolute threshold, threshold of conscious perception, and difference threshold.
What is the absolute threshold?
The minimum intensity at which a stimulus will be transduced (converted into an action potential). It is a threshold in sensation, not perception.
What is the threshold of conscious perception?
Stimulus arrives at the CNS but does not reach higher order brain regions that control attention and consciousness. AKA subliminal perception.
What is the difference threshold?
The minimum difference in magnitude between two stimuli before one can perceive this difference.
What is Weber’s Law?
Weber’s Law states that there is a constant ratio between the change in stimulus magnitude need to produce a jnd (just noticeable difference) and the magnitude of the original stimulus.
Ex. People can differentiate between 440Hz and 443Hz. jnd = 3Hz/440Hz x100 = 0.68% for sound frequency. Therefore people should be able to differentiate between 1000Hz and 1006.8Hz but not between 1000Hz and 1003Hz.
What is signal detection theory?
Perception of stimuli can be affected by nonsensory factors, such as experience (memory), motives, and expectations.
Ex. Responding to someone calling your name in a crowd depends on the size of the crowd, your expectation of being called, and social factors.
What is response bias?
Tendency of subjects to systematically respond to a stimulus in a particular way due to nonsenory factors. Found in signal detection experiments consisting of many trials. During each trial a subject may or may not be presented with a stimulus. There are four possible outcomes: hits, misses, false alarms, and correct negatives.
What is adaptation?
Our detection of a stimulus can change over time. It has a physiological and psychological component. “Getting used to something”
Ex. Once we’re dresses, we stop feeling the clothes on our bodies until we have reason to think about them.
List the structures in the visual pathway from where light enters to projection areas in the brain.
Cornea –> pupil –> lens –> vitreous –> retina (rods & cones –> bipolar cells –> ganglion cells) –> optic nerve –> optic chiasm –> Optic tract –> lateral geniculate nucleus (LGN) of thalamus –> radiations through parietal and temporal lobe –> visual cortex (occipital lobe)
Describe the functions of the cornea, iris, and lens.
Cornea: gathers and filters incoming light
Iris: color part of eye, divided between anterior and posterior chambers. Contains the dilator and constrictor pupillae which open and close the pupil.
Lens: refracts incoming light to focus it on the retina, it is held in place by suspensory ligaments connected to the ciliary muscle.
Describe the function of canal of Schlemm and retina.
Canal of Schelmm: Located in the front of the eye, drains aqueous humor.
Retina: Located on back of the eye, contains rods and cones. It converts incoming photons of light to electrical signals. The central part of the retina is called the macula which has a high concentration of cones. The center of the macula is the fovea.
What is the difference between rods and cones?
They are both photoreceptor cells.
Cones: used for color vision, effective in bright light and come in three forms based on their absorption of light (short/blue, medium/green, long/red).
Rods: specialized for light and dark detection, function best in dim lighting. They have low sensitivity to details but aid in night vision.
