Accommodation
Helps determine depth.
Beta effect
The perception of motion that occurs when different images are presented next to each other in succession
Binocular depth cues
Depth cues that are created by retinal image disparity — that is, the space between our eyes — and which thus require the coordination of both eyes
Blind spot
A hole in our vision because there are no photoreceptor cells at the place where the optic nerve leaves the retina
Colour blindness
The inability to detect green and/or red colours
Cones
Visual neurons that are specialized in detecting fine detail and colours
Convergence
The inward turning of our eyes that is required to focus on objects that are less than about 50 feet away from us
Cornea
A clear covering that protects the eye and begins to focus the incoming light
Depth cues
Messages from our bodies and the external environment that supply us with information about space and distance.
Electromagnetic energy
Pulses of energy waves that can carry information from place to place
Farsighted
When the focus is behind the retina
Feature detector neurons
Specialized neurons, located in the visual cortex, that respond to the strength, angles, shapes, edges, and movements of a visual stimulus
Fovea
The central point of the retina
Gestalt
A meaningfully organized whole
Hue
The shade of a colour
Iris
The coloured part of the eye that controls the size of the pupil by constricting or dilating in response to light intensity
Lens
A structure that focuses the incoming light on the retina
Monocular depth cues
Depth cues that help us perceive depth using only one eye
Nearsighted
When the focus is in front of the retina
Opponent-process colour theory
Proposes that we analyze sensory information not in terms of three colours but rather in three sets of “opponent colours”: red-green, yellow-blue, and white-black
Optic nerve
A collection of millions of ganglion neurons that sends vast amounts of visual information, via the thalamus, to the brain
Phi phenomenon
We perceive a sensation of motion caused by the appearance and disappearance of objects that are near each other
Pupil
A small opening in the centre of the eye
Retina
The layer of tissue at the back of the eye that contains photoreceptor cells
Rods
Visual neurons that specialize in detecting black, white, and gray colours
Trichromatic colour theory
The colour we see depends on the mix of the signals from the three types of cones
Visible spectrum
The part of the electromagnetic spectrum that our eyes detect (only the range from about 400 to 700 billionths of a meter)
Visual accommodation
The process of changing the curvature of the lens to keep the light entering the eye focused on the retina
Visual cliff
A mechanism that gives the perception of a dangerous drop-off, in which infants can be safely tested for their perception of depth
Wavelength
The distance between one wave peak and the next wave peak
Bouncing balls illusion
The tendency to perceive two circles as bouncing off each other if the moment of their contact is accompanied by an auditory stimulus.
Crossmodal phenomena
Effects that concern the influence of the perception of one sensory modality on the perception of another.
Crossmodal receptive field
A receptive field that can be stimulated by a stimulus from more than one sensory modality.
Crossmodal stimulus
A stimulus with components in multiple sensory modalties that interact with each other.
Double flash illusion
The false perception of two visual flashes when a single flash is accompanied by two auditory beeps.
Integrated
The process by which the perceptual system combines information arising from more than one modality.
McGurk effect
An effect in which conflicting visual and auditory components of a speech stimulus result in an illusory percept.
Multimodal
Of or pertaining to multiple sensory modalities.
Multimodal perception
The effects that concurrent stimulation in more than one sensory modality has on the perception of events and objects in the world.
Multimodal phenomena
Effects that concern the binding of inputs from multiple sensory modalities.
Multisensory convergence zones
Regions in the brain that receive input from multiple unimodal areas processing different sensory modalities.
Multisensory enhancement
Multisensory enhancement is observed when the sources of stimulation are spatially related to one another.
Primary auditory cortex
A region of the cortex devoted to the processing of simple auditory information.
Primary visual cortex
A region of the cortex devoted to the processing of simple visual information.
Principle of Inverse Effectiveness
The finding that, in general, for a multimodal stimulus, if the response to each unimodal component (on its own) is weak, then the opportunity for multisensory enhancement is very large. However, if one component—by itself—is sufficient to evoke a strong response, then the effect on the response gained by simultaneously processing the other components of the stimulus will be relatively small.
Receptive field
The portion of the world to which a neuron will respond if an appropriate stimulus is present there.
Rubber hand illusion
The false perception of a fake hand as belonging to a perceiver, due to multimodal sensory information.
Sensory modalities
A type of sense; for example, vision or audition.
Spatial principle of multisensory integration
The finding that the superadditive effects of multisensory integration are observed when the sources of stimulation are spatially related to one another.
Superadditive effect of multisensory integration
The finding that responses to multimodal stimuli are typically greater than the sum of the independent responses to each unimodal component if it were presented on its own.
Unimodal
Of or pertaining to a single sensory modality.
Unimodal components
The parts of a stimulus relevant to one sensory modality at a time.
Unimodal cortex
A region of the brain devoted to the processing of information from a single sensory modality.