Chapter 4: Sensation and Perception Flashcards
Sensation
The process of turning the energy of stimuli picked up by our senses into neural impulses in our brains
Perception
Organization, identification, and interpretation of sensory signals in order to form mental representations of events in the world
Transduction
the transformation of physical stimuli (sights, sounds, smells) into neural impulses located in eyes, ears, skin etc..
bottom-up processing
to construct perception, the brain uses the sensory information
top-down processing
to construct perception, the brain used information already stored in the brain
Psychophysics
investigates the relationship between physical events and conscious experience
Absolute Threshold
Minimal intensity needed to just barely detect a stimulus
Difference threshold
The smallest possible change between two stimuli (colour, tone, etc.) that is barely detectable
Weber’s Law
two stimuli must differ by a minimum proportion to be perceived different
Sensory adaptation
the process by which our brain cells become less sensitive to constant stimuli that are picked up by our senses
Selective attention
the act of focusing on a particular object for a while, simultaneously ignoring distractions and irrelevant information
Inattentional blindness
people failing to notice existence of unexpected objects in their visual field when their attention is engaged with another task
Change blindness
obvious changes in a visual scene are not noticed due to the lack of visual attention
Intensity
the amount of energy in light waves (determined by a wave’s amplitude, or height), influences brightness
Wavelength
the distance from the peak of one wave to the peak of the next
Hue (colour)
related to the wavelength of the light
The Eye Structure
- Cornea: Transparent tissue where light enters the eye. Acts as a lens to focus light into the eye.
- Iris: Muscle that expands and contracts to change the size of the opening (pupil) for light.
- Lens: Focuses the light rays on the retina.
- Retina: Contains sensory receptors (transducers) that process visual information and sends it to the brain.
Accommodation
The process by which the eye’s lens changes shape to focus near or far objects on the retina
Fovea
Central point in the retina around which the eye’s cones cluster and provides the highest visual acuity (ability to see fine details)
Optic nerve
Carries neural impulses from the eye to the brain
Blind spot
spot in the retina where the optic nerve connects and there are no light-sensitive cells so this part of your retina can’t see
Trichromatic theory
the eye contains three types of cone receptors that are sensitive to red, blue and green colours
Visual Form Agnosia
inability to recognize objects by sight
Perceptual Constancy
perceiving a familiar object as having a constant shape, size and brightness despite the stimuli
Size constancy
seeing objects as the same size even if the image on the retina becomes smaller
Depth perception
the ability to judge how far away an object is, can be calculated by using Binocular and Monocular Cues
Binocular Disparity
our two eyes view the world from different angles, provide information about depth, different in image location seen by left of right eye
Interposition
When one object appears to block the view of another, we perceive the blocking object as being closer than the object being blocked
Relative Size
If two objects are similar in size, we perceive the one that casts a smaller retinal image to be farther away
Linear Perspective
Parallel lines appear to converge in the distance. The more the lines converge, the greater their perceived distance
Relative Height
We perceive objects that are closer to the horizon in our field of vision to be farther away than those that are lower
Relative motion
Objects closer to a fixation point move faster and in opposing direction to those objects that are farther away from a fixation point, moving slower and in the same direction
Sound Waves
changes in air pressure over time causing compressing and expanding of the air molecules
Hearing
- Intensity: Amount of energy in a wave, determines the amplitude, relates to the perceived loudness
- Pitch is related to the frequency of a sound.
Frequency is the inverse of the wavelength of
sound
Complexity
the mix of frequencies and changes in amplitude
that make up a sound
Ear structure
- Outer Ear: Collects and sends sounds to the eardrum.
- Middle Ear: Chamber between eardrum and cochlea containing three tiny bones that amplify the vibrations of the eardrum on the cochlea’s oval window
- Inner Ear: Innermost part of the ear, containing the cochlea, semicircular canals, and vestibular sacs
Cochlea
Coiled, bony, fluid-filled tube in the inner ear, it contains basilar membrane
sensorineural hearing loss
Exposure to loud sounds can cause damage to the inner ear, especially the hair cells
conduction hearing loss
Structures of the middle and inner ear can also be damaged by disease or physical trauma
Place Code
high frequencies stimulate hair cells in different locations, basilar membrane
Temporal Code
low frequencies firing rates of hair cells in respond to sound waves
Intensity differences
The head acts as a “shadow” or partial sound barrier
Time differences
Time differences as small as 1/100,000 of a second can cause us to localize sound
somatosenses (body senses)
Touch: pressure, texture, vibration
Thermoreceptors: warmth, cold
Nocioreceptors: pain
Nociceptors
sensory receptors whose signals are interpreted by the brain as pain
Gate-Control Theory
neurons in the spinal cord act as “gates” that can block or transmit pain signals to the brain
vestibular sense
informs us if our body is in motion and tells us to orientate with gravity
Kinesthesis (“movement feeling”)
sensing the movement and position of individual
body parts relative to each other
olfactory bulb
neural structure of forebrain involved in the sense of smell influencing memory and emotion
Sensory interaction
occurs when different senses influence each other, flavour of a food is a sensory interaction between its taste, smell and, pain receptors (hot spice) and texture
