Chapter 4 - Sensation & Perception Flashcards
Sensation
the sense organs’ detection of external stimuli, their responses to the stimuli, and the transmission of these responses to the brain
Perception
the processing, organization, and interpretation of sensory signals; it results in an internal representation of the stimulus
Psychologists divide the world into two distinct phases, what are they?
Sensation and Perception
Sensory Coding
Process of our sensory organs translate the physical properties of stimuli into patterns of neural impulses
Transduction
a process by which sensory receptors produce neural impulses when they receive physical or chemical stimulation
Sensory Receptors
specialized cells in the sense organs, that receive physical or stimulation and pass the resulting impulses to connection neurons (most of this goes through the thalamus)
Steps of Sensation to Perception
1) Stimulus 2) Sensation (sensory receptors DETECT a stimulus) 3) Sensory Coding (stimulus TRANSDUCED - translated into chem/elec signals transmitted to the brain) 4) Perception (neural sigs processed and representation made in brain)
What types of information about a stimulus does the brain need to function effectively?
Qualitative (most basic qualities - ex: horn honk) and Quantitative (degree or magnitude of those qualities - loudness of honk)
What do sensory receptors do in terms of telling the brain about information?
They do coarse coding, called this because sensory qualities are only by a few different receptors - combined responses from different receptors allow us to differentiate between stimuli
Taste (Stimuli, Receptors, Pathways to the Brain)
Molecules dissolved in fluid on the tongue; cells in taste buds on the tongue; portions of facial, glossopharyngeal, and vagus nerves
Smell (Stimuli, Receptors, Pathways to the Brain)
Molecules dissolved in fluid on mucous membranes in the nose; sensitive ends of olf neurons in mucous memb; olfactory nerve
Touch (Stimuli, Receptors, Pathways to the Brain)
Pressure on skin; sensitive ends of touch neurons in skin; Cranial nerves for touch abv the neck spinal nerves for touch elsewhere
Hearing (Stimuli, Receptors, Pathways to the Brain)
Sound waves; pressure-sensitive hair cells in cochlea of inner ear; auditory nerve
Vision (Stimuli, Receptors, Pathways to the Brain)
Light waves; light-sensitive rods and cones in retina of eye; optic nerve
Psychophysics
a subfield developed in 1800’s (Weber & Fechner), examines our psychological experiences of physical stimuli
Absolute Threshold
minimum intensity of stimulation that must occur before you experience a sensation (level of intensity at which participants correctly detect a stimulus on 50% of the trials in which it is presented)
Difference Threshold
the just noticeable difference two stimuli (ex: minimum change in volume for you to notice difference between TV show and commercials)
Weber’s Law
the just noticeable difference between 2 stimuli is based on the proportion of the original stimulus rather than the fixed amount of difference (the more intense the stimulus, the bigger the change needed for you to notice)
What was the problem with classical psychophysics that had to be corrected?
it’s based on the idea of a sensory threshold, so you either notice or don’t notice something (above or below a sensory threshold), but human judgement is what they forgot that comes into play - if you’re doing research on someone, then someone will make the judgement something is happening they wouldn’t normally notice
SDT
(Signal Detection Theory) a theory of perception based on the idea that the detection of a faint stimulus requires a judgement- it is not an all-or-nothing process (classical psychophysics thought of sensory judgements as a yes/no deal)
What are the different outcomes for a signal detection study?
participant tries to figure out if they sensed a stimulus - 4 outcomes - hit (detect real signal), miss (don’t detect signal), false alarm (detect signal not presented), correct rejection
How do you determine a participant’s sensitivity in a signal detection study?
compare hit rate with the false alarm rate - helps correct for biases participant might bring in
Response bias
participant’s tendency to report detecting the signal in an ambiguous trial - some participants take a lot of evidence, others don’t to respond
Sensory adaptation
a decrease in sensitivity to a constant level of stimulation (ex: you don’t notice sound of constant construction or trains going by after a while) - you’ll notice a change either way though - an increase or stopping the cts stimulation
Haptic Sense
the sense of touch (conveys sensations of temperature, pressure, and pain, along with where our limbs are in space)
Tacile stimulation
anything that makes contact with our skin provides this and gives us the experience of touch (skin is largest organ for sensory reception)
How is temperature information sent to the brain?
There are sensory receptors that reach to the skin (long axons go from skin to CNS through spinal cord/cranial nerves), temp receptors have separate cold/hot receptors (intense stimuli can trigger both and make you feel wet)
How is pressure information sent to the brain?
There are sensory receptors that reach to the skin (long axons go from skin to CNS through spinal cord/cranial nerves), pressure works on skin hair movement, also pressure receptor capsules in skin (respond to cts vibration, light fast pressure, light slow pressure, stretching&steady pressure)
How is pain info sent to the brain?
receptors found throughout body, not just in skin send signals through nervous sys
How are pain signals different from temp and pressure?
Nerve fibers that convey pain are thinner and found in all body tissues that sense pain (not so for temp/pressure), also, actual experience of pain is totally created in the brain, and is why phantom limb syndrome patients can feel pain in a missing limb - brain misinterprets it
What the types of nerve fibers for pain? What makes them different?
Fast fibers (sharp, immediate pain), slow fibers (chronic, dull, steady pain), different because fast are myelinated and slow aren’t, so signal that travels from receptors to spinal cord go faster
How do we react and benefit from fast fibers, and how is it activated?
react by recoiling, so it benefits us by protecting us, activated by strong physical pressure/temp extremes
How do we react and benefit from slow fibers, and how are they activated?
react by not using the affected body plans and helps with recuperation, and activated by chemical changes in tissue when skin is damaged
How does sensation occur and where does this info go?
Sensory receptors transduce stimuli into electrical impulses, and nerves then transmit those impulses to the brain, all info except olfaction goes through thalamus
Where does all touch information go?
goes to thalamus, then projected to the primary somatosensory cortex, in parietal lobe