Module 4: Sensation and Perception (4.1) Sensation and Perception ...
Module 4: Sensation and Perception (4.1) Sensation and Perception at a Glance Sensation – Process of detecting external events by sense organs and turning them into neural signals Perception – Involves attending to, organizing, and interpreting stimuli that we sense Sensory Receptors – Structures that respond to external stimuli Transduction – Process in which physical or chemical stimulation is converted into nerve impulse that is relayed to the brain Sensory Adaptation – Reduction of activity in sensory receptors with repeated exposure to a stimulus Sense Stimuli Type of Receptor Vision Light Waves Light-sensitive structures at back of eye Hearing
Sound Waves
Hair cells that respond to pressure change in the ear Different types of nerve endings that respond to pressure, temp changes, and pain
Touch
Pressure/Stretching/Piercing of the skin surface
Taste
Chemicals on the tongue and mouth
Cells lining the taste buds of tongue
Smell
Chemicals contacting mucus-lined membranes of the nose
Nerve endings that respond selectively to different compounds
Steps of sensation to perception: Stimulus -> Sensory Receptors -> (Transduction) -> Neural Impulses -> Perception Psychophysics – Field of study that explores how physical energy such as light and sound and their intensity related to psychological experience Absolute Threshold – Minimum amount of energy/quantity of stimulus needed for it to be dependably detected at least 50% of the time it’s presented Difference Threshold – Smallest detectable difference between stimuli Signal Detection Theory – States whether a stimulus is perceived depends on both sensory experience and judgment made by the subject Gestalt Psychology – Approach to perception that emphasizes “the whole is greater than the sum of its part” Top-Down Processing – Occurs when prior knowledge and expectations guide what is perceived Bottom-Up Processing – Constructing a whole stimulus/concept from parts of raw sensory info Parallel Processing – Refers to simultaneous use of top-down and bottom-up processing as we perceive and interpret the world
Inattentional Blindness – Failure to notice clear visible events or objects because attention is directed elsewhere
(4.2) Visual System Light – Radiation that occupies relatively narrow band of electromagnetic spectrum; travel in waves varying in two properties (length and amplitude) Wavelength – Distance between peaks of wave (Long = Reddish; Short = Bluish) Sclera – White, outer surface of eye Cornea – Clear layer that covers front portion of the eye and contributes to eye’s ability to focus; light enters through cornea and passes through pupil Pupil – Regulated amount of light that enters by changing its size; dilates to allow more light to enter and constricts to allow less light into eye Iris – Round muscle that adjusts the size of pupil; gives eye their characteristic color Lens – Clear structure that focuses light onto back of eye Retina – Lines the inner surface of eye and consists of specialized receptors that absorb light and send signals related to properties of light to the brain Photoreceptors – Specialized receptors of the retina (Rods and cones) Rods – Occupy peripheral regions of the retina; highly sensitive under low light levels Cones – Sensitive to different wavelengths of light that we perceive as color Fovea – Central region of the retina that contains the highest concentration of cones Dark Adaptation – Process by which rods and cones become increasingly sensitive to light under low levels of illumination Optic Nerve – Cluster of neurons that gather sensory info, exit at back of eye, and connect with brain (Creates an area on retina with no rods or cones called optic disc because it travels through back of eye) Blind Spot – Space in retina that lacks photoreceptors Optic Chiasm – Where optic nerves form left and right eyes converge Binocular Depth Cues – Distance cues that are based on the differing perspectives of both eyes Convergence – Occurs when eye muscles contract so that both eyes focus on single object Retinal/Binocular Disparity – Difference in relative position of an object as seen by both eyes which provides info to the brain about depth Monocular Cues – Depth cues that we perceive with only one eye Trichromatic Theory – Maintains that color vision is determined by three different cone types that are sensitive to short, medium, and long wavelengths of light Opponent-Process Theory – States that we perceive color in terms of opposite ends of spectrum (Red -> Green, Yellow -> Blue, White -> Black)
(4.3) Auditory System Frequency – Wavelength (Hz); the number of cycles sound wave travels per second Pitch – Perceptual experience of sound wave frequencies Amplitude – Loudness (dB) Cochlea – Fluid-filled membrane that is coiled in a snail-like shape and contains structures that convert sound into neural impulses
Sound Localization – Process of identifying where sound comes from (Handled by midbrain structure known as inferior colliculus) Place Theory of Hearing – States that how we perceive pitch is based on the location (place) along the basilar membrane that sound stimulates Frequency Theory – Perception of pitch is related to the frequency at which basilar membrane vibrates Primary Auditory Cortex – Major perceptual center of the brain involved in perceiving what we hear
(4.4) Touch and Chemical Senses Haptics – Active, exploratory aspect of touch sensation and perception Kinesthesis – Sense of bodily motion and position Nociception – Activity of nerve pathways that respond to uncomfortable stimulation Gate-Control Theory – Explains our experience of pain as an interaction between nerves that transmit pain messages and those that inhibit these messages Gustatory System – Functions in the sensation and perception of taste Olfactory System (Smell) – Detection of airborne particles with specialized receptors located in the nose Olfactory Epithelium – Thin layer of cells that are lined by sensory receptors (Cilia)
Sound Waves
Hair cells that respond to pressure change in the ear Different types of nerve endings that respond to pressure, temp changes, and pain
Touch
Pressure/Stretching/Piercing of the skin surface
Taste
Chemicals on the tongue and mouth
Cells lining the taste buds of tongue
Smell
Chemicals contacting mucus-lined membranes of the nose
Nerve endings that respond selectively to different compounds
Steps of sensation to perception: Stimulus -> Sensory Receptors -> (Transduction) -> Neural Impulses -> Perception Psychophysics – Field of study that explores how physical energy such as light and sound and their intensity related to psychological experience Absolute Threshold – Minimum amount of energy/quantity of stimulus needed for it to be dependably detected at least 50% of the time it’s presented Difference Threshold – Smallest detectable difference between stimuli Signal Detection Theory – States whether a stimulus is perceived depends on both sensory experience and judgment made by the subject Gestalt Psychology – Approach to perception that emphasizes “the whole is greater than the sum of its part” Top-Down Processing – Occurs when prior knowledge and expectations guide what is perceived Bottom-Up Processing – Constructing a whole stimulus/concept from parts of raw sensory info Parallel Processing – Refers to simultaneous use of top-down and bottom-up processing as we perceive and interpret the world
Inattentional Blindness – Failure to notice clear visible events or objects because attention is directed elsewhere
(4.2) Visual System Light – Radiation that occupies relatively narrow band of electromagnetic spectrum; travel in waves varying in two properties (length and amplitude) Wavelength – Distance between peaks of wave (Long = Reddish; Short = Bluish) Sclera – White, outer surface of eye Cornea – Clear layer that covers front portion of the eye and contributes to eye’s ability to focus; light enters through cornea and passes through pupil Pupil – Regulated amount of light that enters by changing its size; dilates to allow more light to enter and constricts to allow less light into eye Iris – Round muscle that adjusts the size of pupil; gives eye their characteristic color Lens – Clear structure that focuses light onto back of eye Retina – Lines the inner surface of eye and consists of specialized receptors that absorb light and send signals related to properties of light to the brain Photoreceptors – Specialized receptors of the retina (Rods and cones) Rods – Occupy peripheral regions of the retina; highly sensitive under low light levels Cones – Sensitive to different wavelengths of light that we perceive as color Fovea – Central region of the retina that contains the highest concentration of cones Dark Adaptation – Process by which rods and cones become increasingly sensitive to light under low levels of illumination Optic Nerve – Cluster of neurons that gather sensory info, exit at back of eye, and connect with brain (Creates an area on retina with no rods or cones called optic disc because it travels through back of eye) Blind Spot – Space in retina that lacks photoreceptors Optic Chiasm – Where optic nerves form left and right eyes converge Binocular Depth Cues – Distance cues that are based on the differing perspectives of both eyes Convergence – Occurs when eye muscles contract so that both eyes focus on single object Retinal/Binocular Disparity – Difference in relative position of an object as seen by both eyes which provides info to the brain about depth Monocular Cues – Depth cues that we perceive with only one eye Trichromatic Theory – Maintains that color vision is determined by three different cone types that are sensitive to short, medium, and long wavelengths of light Opponent-Process Theory – States that we perceive color in terms of opposite ends of spectrum (Red -> Green, Yellow -> Blue, White -> Black)
(4.3) Auditory System Frequency – Wavelength (Hz); the number of cycles sound wave travels per second Pitch – Perceptual experience of sound wave frequencies Amplitude – Loudness (dB) Cochlea – Fluid-filled membrane that is coiled in a snail-like shape and contains structures that convert sound into neural impulses
Sound Localization – Process of identifying where sound comes from (Handled by midbrain structure known as inferior colliculus) Place Theory of Hearing – States that how we perceive pitch is based on the location (place) along the basilar membrane that sound stimulates Frequency Theory – Perception of pitch is related to the frequency at which basilar membrane vibrates Primary Auditory Cortex – Major perceptual center of the brain involved in perceiving what we hear
(4.4) Touch and Chemical Senses Haptics – Active, exploratory aspect of touch sensation and perception Kinesthesis – Sense of bodily motion and position Nociception – Activity of nerve pathways that respond to uncomfortable stimulation Gate-Control Theory – Explains our experience of pain as an interaction between nerves that transmit pain messages and those that inhibit these messages Gustatory System – Functions in the sensation and perception of taste Olfactory System (Smell) – Detection of airborne particles with specialized receptors located in the nose Olfactory Epithelium – Thin layer of cells that are lined by sensory receptors (Cilia)
