Sensation and Perception Flashcards
Sensation
~The conversion, or transduction, of physical, electromagnetic, auditory and other information from the internal and external environment into electrical signals in the nervous system.
~This is done by receptors in the PNS.
~The water is hot or cold.
Perception
~The processing of sensory information to make sense of its significance.
~Helps us make sense of the world.
~People might perceive hot or cold water differently.
Sensory Receptors
~Nerves that respond to stimuli and trigger electrical signals.
~Sensory stimuli are transmitted to projection areas.
Sensory Ganglia
~Collections of cell bodies outside the CNS.
Photoreceptors
~Respond to electromagnetic waves in the visible spectrum.
~Brightness, color and shape.
Hair Cells
Respond to movement of fluid in the inner ear structures.
Nociceptors
Respond to painful or noxious stimuli.
Thermoreceptors
Respond to changes in temperature.
Osmoreceptors
Respond to the osmolarity of the blood.
Olfactory Receptors
Respond to volatile compounds.
Taste Receptors
Respond to dissolve compounds.
Threshold
The minimum stimulus that causes a change in signal transduction.
Absolute Threshold
~The minimum intensity at which a stimulus will be transduced (converted into action potentials)
~Minimum stimulus energy that is needed to activate the sensory system.
Threshold of Conscious Perception/ Subliminal Perception
~The minimum stimulus energy that will create a signal large enough in size and long enough in duration to be brought into awareness.
Absolute Threshold vs Subliminal Perception
~A stimulus below the absolute threshold will not be transduced and will NOT reach the CNS.
~A stimulus bellow the subliminal perception will arrive to the CNS, but does not reach the part of the brain that controls attention and consciousness.
Difference Threshold/ Just-Noticeable Difference
~The minimum difference in magnitude between tow stimuli before one can perceive this difference.
Weber’s Law
~Relates to the difference threshold
~The jnd for a stimulus is proportional to the magnitude go this stimulus, and that this is proportion is constant over most of the range of possible stimuli.
~Difference/Original = 0.68
~This appears to be accurate for al sensory modalities, except at the extremely high and low ends of each range.
Signal Detection Theory
~Refers to the effects of nonsesnsory factors, such as experiences, motives and expectations, on perception of stimuli.
~Focuses on the change in out perception if the same stimuli depending on both internal (physiological) and external (environmental) context.
Response Bias
~Refers to the tendency of subjects to systematically respond to a stimulus in a particular way due to nonsensory factors.
~A significant of false alarms and misses in a signal detection experiment is an indication of response bias.
Signal Detection Experiments
~Catch Trials –> The signal is present.
~Noise Trials –> The signal is not present.
~If signal is present and subject’s response is YES then –> Hit.
~If signal is present and subject’s response is NO –> Miss.
~If signal is absent and subject’s response is YES –> False Alarm.
~If signal is absent and subject’s response is NO –> Correct Negative.
Adaptation
~Decrease in response to a stimulus over time. Both physiological and psychological component
~Increases the difference threshold.
Sclera
The white part of the eye.
Choroidal Vessels and Retinal Vessels
They supply the eye with nutrients.
Retina
~The innermost layer of the eye.
~Contains photoreceptors that transduce light into electrical information.
Cornea
~Light passes first through here.
~Gathers and focuses the incoming light.
Iris
~The colored part of the eye.
~Divides the front of the eye between the anterior and posterior chambers.
~Contains two muscles: dilator papillae and constrictor papillae.
Dilator Pupillae
Opens the pupil under sympathetic stimulation
Constrictor Pupillae
Constricts the pupil under parasympathetic stimulation.
Ciliary Body
Produces aqueous humor that bathes the front part of the eye before draining into the Canal of Sclemm
Lens
~Refracts incoming light to focus it on the retina and is help in place by the suspensory ligaments connected to the ciliary muscle.
~Behind this lies the vitreous –> a transparent gel that supports the retina.
Ciliary Muscle
~Contraction of this is done under the parasympathetic nervous system.
~When it contracts it pulls on the suspensory ligaments and changes the shape of the lens (accommodation)
Retina
~Is in the back of the eye.
~Consists of neural elements and blood vessels.
~Converts incoming photons of light to electrical signals.
Considered a part of the CNS
~Contains photoreceptors (duplexity or duplicity theory of vision).
Cones
~Comes in three forms (short-, medium- and long-wavelength) to detect colors.
~Senses fine details.
Rods
~Senses light and dark due to the fact that they contain rhodopsin.
~More functional in reduced illumination.
~Low sensitive to detail and are not involved in color vision, but permit night vision.
~There are more rods than cones in the human eye.
Macula
~The central section fo the retina.
~high concentration of cones.
Fovea
~Contains only cones.
~As you move farther away from the fovea, the concentration of rods increase while the concentration of cones decrease.
~Visual acuity is best here.