Sensation & Perception Flashcards
What is the difference between sensation and perception?
Sensation is the process of gathering sensory information about the environment and transmitting it to the brain; perception is the process of organising and interpreting the sensations
How does sensation begin?
With a detectable stimulus
What is the absolute threshold?
The minimum stimulus intensity required for detection (detected 50% of the time)
What is the signal-detection theory?
Sensation = Sensory processes + decision processes
What is the difference threshold?
The lowest level of stimulation required to sense that a change in stimulation has occurred (a just noticeable difference)
Are sensation and perception passive or active processes?
Active
What is the evolutionary perspective of sensory and perceptual processes?
They reflect the impact of adaptive pressures
What are the five common features of the senses?
1) They must translate physical stimuli into sensory signals
2) They have thresholds
3) Sensation requires constant decision-making
4) Ability to detect changes in stimuli
5) Ability to tune out stimuli that continue without change
What is transduction?
The process of converting physical energy or stimulus information into neural impulses
For what two features does the brain code sensory stimulation?
Intensity and quality
What are the three laws regarding difference thresholds?
Weber’s, Fechner’s and Stevens’ power laws
What is adaptation?
Sensory receptors respond less to stimuli with repeated exposure
When do feature detectors in the primary visual cortex respond?
When stimulation in their receptive field matches a particular pattern or orientation
What do the ventral and dorsal visual pathways process?
Ventral: Form & colour
Dorsal: Depth & motion
What is the trichromatic theory?
The eye has 3 receptors for red, green and blue
What is the opponent-process theory?
There are three antagonistic colour systems: blue/yellow, red/green and black/white
What is the stimulus for hearing?
Sound waves
What is sound wave frequency experienced as?
Pitch
What is the place theory of hearing?
Perception of pitch corresponds with different places along the basilar membrane
What is the frequency theory of hearing?
Perception of pitch corresponds to the frequency at which the entire membrane vibrates
What is the travelling-wave theory of hearing?
The whole membrane moves, but waves peak at different places
What two cues are critical for auditory localisation?
Intensity (loudness) and timing of the sounds arriving at each ear
What is the pathway for smell?
Olfactory cilia - neural impulse - olfactory nerve - olfactory bulb
What is the gate control theory of pain?
Incoming pain sensation pass through a gate in the spinal cord that can be closed to block pain signals
What is kinaesthesia?
Knowing the position of the various parts of the body
What is form perception?
The organisation of sensations into meaningful shapes and patterns
What are the four aspects of perceptual organisation?
Form perception, depth/distance perception, motion perception & perceptual constancy
What are the Gestalt principles of form perception?
Pragnanz/simplicity, similarity, good continuation, proximity and closure
What is the recognition-by-components theory?
People perceive and categorise objects by first breaking them down into elementary units
What are perceptual illusions?
Perceptual misinterpretations produced by normal perceptual processes
What is the law of pragnanz?
Also known as the law of good figure and law of simplicity; every stimulus is organised to be perceived in the simplest form possible (e.g. heart with arrow)
What is the law of similarity?
Similar things are grouped together
What is the law of good continuation?
The brain organises things into continuous lines or patterns
What is the law of proximity?
Things that are near each other appear to be grouped together
What is the law of closure?
Whenever possible, people see incomplete figures as complete
What is depth/distance perception?
The organisation of perception in three dimensions
What are binocular cues?
Cues from both eyes together
What are two types of binocular cues?
Retinal disparity (e.g. colourblind chart) and convergence
What are monocular cues?
Cues from a single eye
What are three types of monocular cues?
Linear perspective (e.g. train tracks), texture gradient (e.g. blurring) and shading
What does motion perception rely on?
Motion detectors from the retina through the cortex
What is perceptual constancy?
The organisation of changing sensations into percepts that are relatively stable
What are the three types of perceptual constancy?
Colour, shape and size constancy
What is bottom-up processing?
Processing that begins with raw, sensory data that feed up to the brain
What is top-down processing?
Begins with the observer’s expectations and knowledge
