Sensation, Perception, & Cognition Ch:30
Special sensory areas of brain receive & interpret stimuli from the sensory receptors.
Structures concerned with sense of smell & taste.
Sensory Systems
•Vision
•Hearing
•Taste
•Smell
•Touch
•Our sense of our body in space all help us to interpret & interact with our environment
in a meaningful way.
•To grow, develop, & function, we must be able to sense & respond to sensory input.
The Senses
•Provide information about
•Internal environment
•External environment
•Enable people to experience the world
•Our senses give us information about environment inside & outside of our bodies.
•Purpose of sensation is to allow body to respond to changing situations & maintain
homeostasis.
•Sensory experience involves 4 components in nervous system: stimulus, reception,
perception, & arousal mechanism.
•Allow response to changes
•Help body maintain homeostasis
•Necessary for human growth & development
Components of the Sensory Experience
Stimulus
•Trigger that stimulates receptor
, •Meaning depends on reception & processing
•loud noise
•bright light
•sour fruit
Reception
•Receptor converts a stimulus to nerve impulse & transmits impulse along sensory
neurons to CNS.
•Some receptors remain activated for as long as stimulus is applied
that is, their response declines with time.
•Adaptation explains why, over time, you become unaware of unpleasant smell or
persistent hum of air conditioner.
•Occurs through receptors
Thermoreceptors ▪Thermoreceptors in skin detect variations in temperature
Proprioceptors ▪Proprioceptors in skin, muscles, tendons, ligaments, & joint capsules coordinate
input to enable us to sense the position of our body in space (proprioception).
Photoreceptors ▪Photoreceptors located in retina of eyes detect visible light.
Perception
•Ability to interpret sensory impulses
•Ability to give meaning to impulses
•Affected by
Location of receptor
Number of receptors activated
Frequency of action potentials
Changes in above
Brain discards about 99% of all sensory information as irrelevant & unimportant
Arousal
•Composed of consciousness & alertness
•Mediated by reticular activating system (RAS)
•Affected by
Environment
Medications
RAS located in brain stem, controls consciousness & alertness.
-Neurons of RAS make connections between spinal cord, cerebellum, thalamus, & cerebral
cortex, relaying visual, auditory, & other stimuli that help keep us awake, attentive, & observant.
-Without such stimuli, CNS becomes lethargic, & person may lose consciousness.
-Anesthesia, sedatives, opioids, & some other drugs depress the RAS, as does a darkened, quiet
environment.
Response to sensations
Factors affecting response
Intensity of stimulus
Contrasting stimuli
Adaptation to stimuli
Special sensory areas of brain receive & interpret stimuli from the sensory receptors.
Structures concerned with sense of smell & taste.
Sensory Systems
•Vision
•Hearing
•Taste
•Smell
•Touch
•Our sense of our body in space all help us to interpret & interact with our environment
in a meaningful way.
•To grow, develop, & function, we must be able to sense & respond to sensory input.
The Senses
•Provide information about
•Internal environment
•External environment
•Enable people to experience the world
•Our senses give us information about environment inside & outside of our bodies.
•Purpose of sensation is to allow body to respond to changing situations & maintain
homeostasis.
•Sensory experience involves 4 components in nervous system: stimulus, reception,
perception, & arousal mechanism.
•Allow response to changes
•Help body maintain homeostasis
•Necessary for human growth & development
Components of the Sensory Experience
Stimulus
•Trigger that stimulates receptor
, •Meaning depends on reception & processing
•loud noise
•bright light
•sour fruit
Reception
•Receptor converts a stimulus to nerve impulse & transmits impulse along sensory
neurons to CNS.
•Some receptors remain activated for as long as stimulus is applied
that is, their response declines with time.
•Adaptation explains why, over time, you become unaware of unpleasant smell or
persistent hum of air conditioner.
•Occurs through receptors
Thermoreceptors ▪Thermoreceptors in skin detect variations in temperature
Proprioceptors ▪Proprioceptors in skin, muscles, tendons, ligaments, & joint capsules coordinate
input to enable us to sense the position of our body in space (proprioception).
Photoreceptors ▪Photoreceptors located in retina of eyes detect visible light.
Perception
•Ability to interpret sensory impulses
•Ability to give meaning to impulses
•Affected by
Location of receptor
Number of receptors activated
Frequency of action potentials
Changes in above
Brain discards about 99% of all sensory information as irrelevant & unimportant
Arousal
•Composed of consciousness & alertness
•Mediated by reticular activating system (RAS)
•Affected by
Environment
Medications
RAS located in brain stem, controls consciousness & alertness.
-Neurons of RAS make connections between spinal cord, cerebellum, thalamus, & cerebral
cortex, relaying visual, auditory, & other stimuli that help keep us awake, attentive, & observant.
-Without such stimuli, CNS becomes lethargic, & person may lose consciousness.
-Anesthesia, sedatives, opioids, & some other drugs depress the RAS, as does a darkened, quiet
environment.
Response to sensations
Factors affecting response
Intensity of stimulus
Contrasting stimuli
Adaptation to stimuli
