LCT8: Sensation Flashcards
Sensation
the processes by which our sense organs receive information (energy) from the environment
Sensations are…
simple mindless things that happens
Transduction
process through which stimuli reaching the receptors are converted into neural impulses … OR … how physical signals from the environment are changed into the neural signals sent to the brain
Psychophysics
the study of the relationship between physical stimulation and subjective sensations
Absolute threshold
the smallest amount of stimulation that can be detected
Difference threshold
“just noticeable difference” (JND) - the smallest change in a stimulus that can be detected
Signal Detection Theory
theory that focuses on making decisions about stimuli when uncertain - detecting a stimulus is jointly determined by the signal and the subject’s response criterion
Sensory Adaptation
a decrease in sensitivity to a constant level of stimulation
Basic Sensory Processes
- Vision
- Hearing
- Touch
- Taste
- Smell
What kind of neural signals do the eyes transduce light waves into?
electro-chemical neural signals
Where does transduction occur for our vision?
In the rods and cones
Rodes and Cones
photoreceptor cells on the retina
Rods
helps to see in low light, at night, and in peripheral vision - very sensitive, but gray-scale vision
Cones
color vision - less numerous, need high light levels
Where are the rods located?
outer portion of the retina
Where are the cones located?
inner portion of the retina
Ganglion Cells
send signals along their axons, which join to form the Optic Nerve
Blind Spot
where the Optic Nerve leaves the eye (optic disk)
What part of the eye initially captures light?
Photoreceptors
What part of the retina is most sensitive in the dark?
Rods
Optic Nerves
send signals from each eye to the thalamus
Optic Chiasm
where Optic Nerves cross
Visual Cortex
where visual information is transmitted to
Visual Pathway - Stimulas to transduction
Light - cornea - pupil (iris) - lens - retina (rods/cones)
Visual Pathway - Neural pathway
ganglion cells (optic nerves) - optic chiasm - thalamus - primary visual cortex
Where does color come from?
wavelengths reflecting off of objects
Sound waves vary in what?
Frequency (pitch) and amplitude (loudness)
Where does auditory transduction occur?
hair cells in the basilar membrane
Auditory localization
having two ears allows us to locate the source of a sound
Haptic/Cutaneous sense
sensory receptors in the skin detect pressure, temperature, and pain
Tactile stimulation
anything that makes contact with our skin
Pain
crucial but complex sense
Two types of pain transmission fibers
- Sharp pains = fast-acting A-delta fibers
- Dull pains = slow-acting C-fibers
Gate Central Theory of Pain
neural “gates” in the spinal cord control perceptions of pain
Two distinct neural pathways…
- to the somatosensory cortex (thalamus)
- to the emotional centers of the brain (limbic system)
Taste receptors
respond to the chemical substances that produce at least five basic sensations : sweet, sour, salty, bitter, and umami (savory)
Olfactory bulb
brain center for smell
Kinesthetic Sense
ability to judge where one’s limbs are in space (movement, orientation, posture)
Vestibular sense
ability to compare one’s bodily position to the upright position (balance - and movement)
Extrasensory Perception
some people think they have additional sensory systems that allow them to… know what other people are thinking, or to predict the future
