SENSING AND PERCEIVING Flashcards
`Sensation
Awareness resulting from the stimulation of a sense organ
Perception
The organization and interpretation of sensations
Six senses
Seeing, hearing, smelling, touching, tasting, and proprioception
Transduction
The conversion of stimuli detected by receptor cells to electrical impulses that are then transported to the brain
Psychophysics
Branch of psychology that studies the effects of physical stimuli on sensory perceptions and mental states
Absolute threshold of a sensation
The intensity of a stimulus that allows an organism to just barely detect it (about 50% of the time)
Signal detection analysis
Technique used to determine the ability of the perceiver to separate true signals from background noise
“Hit”
Say “yes” when there is a sound
“False alarm”
Say “yes” to no signal
“Miss”
Say “no” when there is a sound
“Correct rejection”
Say “no” when there is no signal
Sensitivity
The true ability of the individual to detect the presence or absence or signals
Response bias
A behavioural tendency to respond “yes” to the trials, which is independent of sensitivity
Difference threshold (JND):
Refers to the change in a stimulus that can just barely be detected by the organism
Weber’s Law
Just noticeable difference of a stimulus is a constant proportion of the original intensity of the stimulus
Subliminal stimuli
Events that occur below the absolute threshold and of which we are not conscious
Blindsight
A condition in which people are able to consciously report on visual stimuli but nevertheless are able to accurately answer questions about what they are seeing
Electromagnetic energy
Pulses of energy waves that can carry information from place to place
Wavelength
The distance between one wave peak and the next wave peak
Visible spectrum
Our eyes only detect the range from about 400 to 700 billionths of a meter
Near sighted
Focus in front of the retina - eye is too long
Far sighted
Focus is behind the retina - eye is too short
Optic nerve
Collection of millions of ganglion neurons that sends vast amounts of visual information, via the thalamus, to the brain
Rods
Visual neurons that specialize in detecting black, white and grey colours - help us see in dim light (at night) and is active in peripheral vision – sensitive to light/dark
Cones
Visual neurons that are specialized in detecting fine detail and colours - colour and bright light - located around the fovea - sensitive to colour
Fovea
the central point of the retina
Blind spot
A hole in our vision - no photoreceptor cells at the place where the optic nerve leaves the retina – but the visual system overcomes this
Feature detector neurons
Specialized neurons, located in the visual cortex, that respond to the strength, angles, shapes, edges and movements of a visual stimulus
Hue
Shade of colour conveyed by the wavelength of the light that enters the eye - length and intensity/height
Trichromatic colour theory
Helmholtz theorized that colour is perceived because the cones in the retina come in three types 1.) Reacts primarily to blue light (short wavelengths) 2.) Reacts primarily to green light (medium wavelengths 3.) reacts primarily to red light (long). The strength of these waves are then compared to create colour
Colour-blindness
The inability to detect green and or red colours
Opponent-process colour theory
Proposes that we analyze sensory information not in terms of 3 colours but rather in three sets of “opponent colours”: red-green, yellow-blue, white-black - neurons in the retina – this explains after images
Figure and ground
We structure input so that we always see a figure (image) against a ground (background)
Similarity
Stimuli that are similar to each other tend to be grouped together
Proximity
We tend to group nearby figures together
Continuity
We tend to perceive stimuli in smooth, continuous ways rather than in more discontinuous ways
Closure
We tend to fill in gaps in an incomplete image to create a complete, whole object
Depth perception
The ability to perceive three - dimensional space and to accurately judge distance
Depth cues
Messages from our bodies and the external environment that supply us with information about space and distance
Binocular depth cues
Depth cues that are created by retinal image (both eyes)
Disparity
Space between our eyes and which therefore require the coordination of both eyes
Convergence
The inward turning of our eyes that is required to focus on objects that are less than about 50 ft away from us
Accommodation
Helps determine depth
Monocular depth cues
Depth cues that help us perceive depth using only one eye
Position
We tend to see objects higher up in our field of vision as father away
Relative size
Assuming that the objects in a scene are the same size, smaller objects are perceived as farther away
Linear perspective
Parallel lines appear to converge at a distance
Light and shadow
The eye receives more reflected lights from objects that are closer to us. Normally, light comes from above, so darker images are in shadow
Interposition
When one object overlaps another object, we view it as closer
Aerial perspective
Objects that appear hazy, or that are covered with smog or dust, appear farther away
Motion parallax
Objects moving at a constant speed across the frame will appear to move a greater amount if they are closer to an observer than they oddly if they were at a greater distance
McGurk Effect
Visual processing, influences auditory processing
Synesthesia
Condition in which people experience cross-modal sensations
Grapheme-colour
See letters/numbers as colours
Lexical-taste
Taste when they read/hear words
Criterion Point
When the presence/absence of the signal is unclear, how likely are you to say it is present?
Beta effect
Refers to the perception of motion that occurs when different images are presented next to each other in succession - the visual cortex fills in the missing part of the motion and we see the object moving
Phi phenomenon
We perceive a sensation of motion caused by the appearance and disappearance of objects that are near each other
Frequency
Wavelength of the sound wave that is measured in terms of the number of the waves that arrive per second and determines our perception of pitch
Pitch
The perceived frequency of a sound - longer sound waves have a lower frequency and produce a lower pitch while shorter waves have a high frequency and produce a higher pitch
Amplitude
Height of the sound wave, determines how much energy it contains - perceived as loudness
Loudness
The degree of sound volume
Decibel
Unit of relative loudness
Cilia
Tip on the hair cells
Frequent theory of hearing
Proposes that whatever the pitch of a sound wave, nerve impulses of a corresponding frequency will be sent to the auditory nerve - this theory causes problems with high pitch sounds but explains low pitch sounds
Place theory of hearing
Proposes that different areas of the cochlea respond to different frequencies - this explains high pitches and also hearing loss that comes with age
Conductive hearing loss
Caused by physical damage to the ear that reduces the ability of the ear to transfer vibrations from the outer ear to the inner ear
Sensorineural hearing loss
Caused by damage to the cilia or to the auditory nerve - less common but frequently occurs with age
Cochlear implant
Device made up of series of electrodes that are placed inside the cochlea - if the auditory nerve is still intact - this utilizes place theory
6 taste sensations
Sweet, salty, sour, bitter, piquancy, and umami
Taste buds
Designed to sense chemicals in the mouth
Olfactory membrane
Located in the upper nasal passage and detects 10 million-20 million receptor cells when we breathe in through our nostrils
Olfactory receptor cells
Topped with tentacle like protrusions that contain receptor proteins
The skin
The largest organ in the body and is the sensory organ for touch
Proprioception
The ability to sense the position and movement of our body parts - specialized neurons
Vestibular system
A set of liquid-filled areas in the inner ear that monitors the head’s position and movement
Semicircular canals
Rotational movement
Vestibular canals
Linear movement
Bottom-up processing
(1) Features of stimulus (2) Combine features into complex forms (3) Recognize stimulus – accurate, detailed, new unfamiliar scenes
Top-down processing
(1) Perceptual Hypothesis (expectations) (2) Select features to analyze (3) Recognize stimulus – fast, easy, not as accurate, reduces the workload
Visual Agnosia
Inability to recognize objects (1) apperceptive agnosia - combining features into objects (2) associative agnosia - can’t name objects
Prosopagnosia
Inability to detect and remember faces
Gate control theory of pain
Proposes that pain is determined by the operation of two types of nerve fibres in the spinal cord, the smaller set carries pain away from the body and the larger set is designed to stop/start the flow of pain
Selective attention
The ability to focus on some sensory inputs while tuning out others
Cocktail party phenomenon
Partying and talking to someone in one part of the room, when suddenly you hear your name being mentioned by someone in another part of the room
Sensory adaptation
A decreased sensitivity to a stimulus after prolonged and constant exposure
Perceptual constancy
The ability to perceive a stimulus as constant despite changes in sensation
Illusions
occur when the perceptual processes that normally help us correctly perceive the world around us are fooled by a particular situation so that we see something that does not exist or that is incorrect
