Unit 4-5 Sensation, Perception, and Consciousness

Sensation

The process by which our sensory organs receive stimulus energies from the environment and transduce them into the electrical energy of the nervous system.

Transduction

The transformation of sensory stimulus energy from the environment into neural impulses.

Perception

The neural processing of electrical signals form an internal mental representation inside your brains of what’s on the outside.

Psychophysics

The study of the relationship between the physical characteristics of environmental stimuli and our mental experience of them.

Absolute threshold

The minimum amount of stimulation necessary for someone to detect a stimulus half of the time.

Signal detection theory

An approach to measuring thresholds that takes into account both the intensity of the stimulus and psychological biases for a more accurate assessment.

Difference threshold

The minimum difference required between two stimuli for an observer to detect a difference half the time

JND (Just-noticeable difference)

The minimum difference required between two stimuli for an observer to detect a difference half the time; also called Difference threshold.

Weber’s Law

The observation that the likelihood of perceiving a stimulus change is proportional to the magnitude of the stimuli

Adaptation

A phenomenon whereby an individual stops noticing a stimulus that remains constant over time, resulting in enhanced detection of stimulus change.

Wavelength

The distance between any two consecutive crests of troughs of a wave

Frequency

The number of cycles per second of a wave

Amplitude

The height of the crests of a wave

Pupil

A hole in the iris where light enters the eye

Iris

The colored Muscle circling the pupil

Lens

A membrane at the front of the eye that focuses the incoming light on the retina

Accommodation

Adjustment of the lens’s thickness by specialized muscles in order to change the degree to which it bends.

Retina

A surface on the back of the eye that contains the photoreceptor

Photoreceptors

Specialized neurons located in the retina at the back of the eye that perform transduction

Rods

Photoreceptor cells that primarily support nighttime vision

Cones

Photoreceptor cells that are responsible for high-resolution color vision

Optic nerve

A bundle of axons that converge from the retina and transmit action potentials to the brain

Blind spot

An area in the middle of the visual field where there are no photoreceptors and no information can be received.

Fovea

A small pit in the center of the retina that is densely packed with cones

Trichromatic theory

A theory of color perception stating that three types of cone cells, each most sensitive to a specific wavelength of light, work together to produce our perception of a multicolored world.

Opponent process theory

A theory of color perceptions stating that information from the cones is separated into three sets of opposing or opponent channels in the ganglion cell layer

Feature detectors

Specialized cells in the visual cortex that respond to basic features such as lines, edges, and angles

Visual association cortex

The region of the brain where objects are reconstructed from prior knowledge and information collected by the feature detectors

Prosopagnosia

A visual disorder in which individuals are unable to recognize the identity of faces

Dichromatism

a type of color vision deficiency (commonly called color blindness) where a person has only two functioning types of cone photoreceptors in their retina instead of the normal three

Monochromatism

complete color blindness

Blindsight

a condition where a person can respond to visual stimuli without consciously experiencing them

Apparent motion

a perceptual illusion where the brain perceives motion in stationary objects or a rapid sequence of static images

Phi phenomenon

A visual illusion in which the flashing of separate images in rapid succession is perceived as fluid movement

Pitch

The perceptual quality of sound that makes a flute sound high and a tuba low

Middle ear

The portion of the ear containing the eardrum and ossicles

Ossicles

Three tiny bones in the ear (the hammer,anvil, and stirrup) that act as levers to amplify incoming sound waves

Inner ear

The innermost part of the ear, where the cochlea resides

Cochlea

A spiral structure in the inner ear where the basilar membrane, containing auditory sensory neurons, is located

Basilar membrane

A structure is the cochlea where the auditory cilia, or auditory sensory neurons

Frequency theory

A theory of pitch perception stating that the brain uses the frequency of auditory sensory neuron firing to indicate pitch

Volley theory

Neurons take turns firing in the ear to hear mid range sounds frequencies

Place theory

 A theory of pitch perception stating that different pitches arise from stimulation at different places along the basilar membrane

Primary auditory cortex

The region of the brain, located in the temporal lobe, where sound is processed

Tonotopic organization

The arrangement of the auditory cortex such that nearby frequencies are processed near each other in the brain, resulting in a sound map

Conduction Deafness

hearing loss caused by damage to the mechanical system that conducts sound waves to the cochlea

Sensorineural Deafness

hearing loss caused by damage to the hair cell receptors in the cochlea or to the auditory nerve that carries signals to the brain

Sound Localization

the auditory system’s ability to identify the origin and direction of sound in 3D space

Tactile

The sense of touch

Primary somatosensory cortex

The region of the brain where the processing of touch sensation occurs

Somatosensory homunculus

A depiction of how the body is represented by the brain, proportional to the amount of cortex devoted to each body part.

Haptic

Examining an object by touch

Proprioception

The sensory system responsible for awareness of body positions

Vestibular system

The sensory system primarily responsible for balance

Kinesthesis

The senses responsible for monitoring the position and movement of the body, including proprioception and the vestibular system

Olfaction

The sense of smell

Epithelium

The mucous membranes in the nasal cavity that contains the olfactory receptor neurons

Olfactory bulb

A structure just above the naval cavity where information is communicated to the primary olfactory cortex via the olfactory tract

Glomeruli

A spherical cluster of neurons in the olfactory bulb

Primary olfactory cortex

The region of the brain, located in the anterior temporal lobe, where smell is processed

Gustation

The sense of taste

Binocular cues

Depth information gathered from the separation between an individual’s two eyes

Binocular disparity

The magnitude of difference between the images projected on an individual’s two eyes

Convergence

a binocular depth cue

Monocular cues

Depth information that can be gathered by only one eye

Relative height (compared to horizon)

higher objects are perceived are farther away

Relative clarity

 sharper objects perceived as closer

Texture gradient

an objects texture gets smoother as it goes into the distance

Interposition

perceiving depth and distance with only one eye

Linear perspective

parallel lines appear to converge in the distance

Relative motion

Judge distance of objects based on how fast they appear to move when you are in motion

Size constancy

The phenomenon whereby the brain adjusts its perception of distance in order to perceive an object’s actual size as constant, taking into account changes in retinal size.

Color constancy

The phenomenon whereby the brain adjusts its perception of color to hold it constant, taking into account changes in lightning conditions.

Perceptual set

A predisposition that influences what we perceive based on recent experience or context

Aftereffects/afterimages

a visual sensation that persists in your field of vision after the original stimulus has been removed

Myopia/nearsightedness

see nearby object clearly, far away objects are blurry

Sensory interaction

one sense can influence/modify/combine with another to shape our perception

Synesthesia

A  neurological condition where the stimulation of one sensory pathway involuntarily leads to an experience in a second sensory pathway

Photopigments

light receptors in the rods and cones

Bipolar cells

the second layer of neurons in the retina that transmit visual signal from photoreceptors to ganglion cells

Ganglion cells

specialized neurons in the retina that receive signals from bipolar cells and transmit the information to the brain

Primary visual cortex

brain region responsible for processing visual information

Ventral

towards the bottom/belly

Dorsal

towards the back

Nociceptor

 a specialized sensory receptor that detects hurtful or harmful stimuli

Thermoceptor

a specialized sensory receptor located in the skin that detects changes in temperature

taste receptors

cells on the tongue that detect dissolved chemicals from food and convert them into neural signals

umami

one of the five basic tastes, savory

Oleogustus

sixth basic taste - fatiness

Supertasters/medium tasters/nontasters

different densities of taste receptors on the tongue

Gate control theory

the spinal cord contains a neurological gate that either opens to let signals travel to the brain or closes to block them

semicircular canals

 three fluid-filled loops located in the inner ear that are responsible for the vestibular sense

Top-Down processing

past knowledge guides interpretation of sensory data

Bottom-Up processing

brain builds perception of world from raw sensory input

Gestalt Psychology

A school of psychological thought that attempted to explain how various elements group together to form objects, arguing that perception is more than a simple piecing together of building blocks

Closure

the brain automatically fills in missing information to view an incomplete figure as a complete whole

Figure and Ground

your brain automatically divides a visual scene into a main focus and a background

Proximity

the brain groups objects that are close to each other in a single unit/pattern

Similarity

the brain groups items together if they share visual features

Consciousness

The moment by moment awareness of the external environment as well as one’s own thoughts, feelings, and behaviors