week 8 - the visual world Flashcards
occipital lobe
Occipital lobe - back part of cerebrum, houses visual areas
pupil
Pupil - small opening in the eye
iris
Iris - coloured portion of the eye, controls size of the pupil by constricting/dilating in response to light surrounds the pupil
cornea
Cornea - A clear covering that protects the eye and begins to focus the incoming light thin layer that protects the eye
lens
A structure that focuses the incoming light on the retina sits just behind the cornea and the iris
Focuses incoming light onto the retina
Flexes to change shape of the retina
visual accommodation
Visual accommodation - The process of changing the curvature of the lens to keep the light entering the eye focused on the retina
near sighted versus far sighted
Near sighted - info far away is improperly focused, lens refracts light
Far sighted - info goes behind the retina
People get lenses or contacts to properly refract the light
retina
Retina - Cell layer in the back of the eye containing photoreceptors.
Every image projected here is actually INVERTED and BACKWARDS
Fovea - The central point of the retina
Where we can see the most precisely, most concentration of cones
Blindspot - A hole in our vision that is created because there are no photoreceptor cells at the place where the optic nerve leaves the retina.
fovea
Fovea - The central point of the retina
Where we can see the most precisely, most concentration of cones
blindspot
Blindspot - A hole in our vision that is created because there are no photoreceptor cells at the place where the optic nerve leaves the retina.
Blind spot - A hole in our vision because there are no photoreceptor cells at the place where the optic nerve leaves the retina
the optic nerve
The optic nerve
A collection of millions of ganglion neurons that sends vast amounts of visual information, via the thalamus, to the brain.
Ganglion cells converge together to make a thicker cord of individual threads Because the retina and this nerve are active processors and analyzers of information, and can be considered an extension of the brain itself.
from the optic nerve to the visual cortex
from optic nerve to visual cortex
Optic nerve from each eye projects to the visual area of the thalamus on both the ipsilateral (same) side and contralateral (opposite) side.
From there, the visual input is processed by visual cortex the ipsilateral side However, our visual cortex processes both eyes separately, and in parallel
feature processing in the visual cortex
Feature processing in visual cortex
Visual cortex has specialized neurons, located in the visual cortex, that respond to the strength, angles, shapes, edges, and movements of a visual stimulus, called feature detector neurons. Neurons in the early visual cortex respond to simple features, but the complexity of features builds up as you move along the ventral pathway (the ‘what’ pathway) Information is also passed along the dorsal pathway (the ‘where’ pathway), which processes information about location and movement.
rods and cones
Rods - Photoreceptors of the retina sensitive to low levels of light. Located around the fovea.
Cones - Photoreceptors of the retina sensitive to color. Located primarily in the fovea.
gestalt principle
Gestalt principles
A whole is more than the sum of its parts
depth perception
Depth perception
binocular disparity
Difference in images processed by the left and right eyes
binocular vision
Our ability to perceive 3D and depth because of the difference between the images on our retinas
depth cues (binocular)
Depth cues (binocular)
convergence
The inward turning of our eyes that is required to focus on objects that are less than about 50 feet away from us
accommodation
Changes of the curvature of the lens to see far or close objects. Information relayed from the muscles in the eye helps us determine distance.
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
depth cues monocular
Depth cues (monocular) Position Relative size Linear perspective Light and shadow Interposition Aerial perspective
Monocular depth cues - Depth cues that help us perceive depth using only one eye
integration
Integration - The process by which the perceptual system combines information arising from more than one sense
Multisensory convergence zones
Multisensory convergence zones - Regions in the brain that receive input from multiple unimodal areas processing different sensory modalities.
spatial principle of mutlisensory integration
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
Analogous to this spatial principle, sources of stimulation that are close together in time are often superadditive as well
rubber hand illusion
Rubber hand illusion - The false perception of a fake hand as belonging to a perceiver, due to multimodal sensory information.
accommodation
Accommodation - Helps determine depth.
beta effect
Beta effect - The perception of motion that occurs when different images are presented next to each other in succession
colourblindness
Colour blindness - The inability to detect green and/or red colours
near and far sightedness
Nearsighted - When the focus is in front of the retina
Farsighted - When the focus is behind the retina
convergence
Convergence - The inward turning of our eyes that is required to focus on objects that are less than about 50 feet away from us
depth cues
Depth cues - Messages from our bodies and the external environment that supply us with information about space and distance.
electromagnetic energy
Electromagnetic energy - Pulses of energy waves that can carry information from place to place
feature detector neurons
Feature detector neurons - Specialized neurons, located in the visual cortex, that respond to the strength, angles, shapes, edges, and movements of a visual stimulus
opponent process colour theory
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
Optic nerve - A collection of millions of ganglion neurons that sends vast amounts of visual information, via the thalamus, to the brain
phi phenomenon
Phi phenomenon - We perceive a sensation of motion caused by the appearance and disappearance of objects that are near each other
trichromatic colour theory
Trichromatic colour theory - The colour we see depends on the mix of the signals from the three types of cones
visible spectrum
Visible spectrum - The part of the electromagnetic spectrum that our eyes detect (only the range from about 400 to 700 billionths of a meter)
sensory modalities
Sensory modalities - A type of sense; for example, vision or audition.
receptive field
Receptive field - The portion of the world to which a neuron will respond if an appropriate stimulus is present there.
principle of inverse affectiveness
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.
primary auditory cortex and visual cortex
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.
mutlisensory convergence zones
Multisensory convergence zones - Regions in the brain that receive input from multiple unimodal areas processing different sensory modalities.
multimodal (+perception) (+phenomena)
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.
visual cliff
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
Wavelength - The distance between one wave peak and the next wave peak
bouncing balls illusion
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, receptive field, and 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.
Cross Modal stimulus - A stimulus with components in multiple sensory modalities that interact with each other
double flash illusion
Double flash illusion - The false perception of two visual flashes when a single flash is accompanied by two auditory beeps.
integrated
Integrated - The process by which the perceptual system combines information arising from more than one modality.
McGurk effect
McGurk effect - An effect in which conflicting visual and auditory components of a speech stimulus result in an illusory percept.
Spatial principle of Multisensory integration
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.
superaddtive effect of Multisensory integration
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/unimodal components/unimodal cortex
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.
How does vision work?
Vision is the process of detecting the electromagnetic energy that surrounds us. Only a small fraction of the electromagnetic spectrum is visible to humans.
The visual receptor cells on the retina detect shape, colour, motion, and depth.
Light enters the eye through the transparent cornea and passes through the pupil at the centre of the iris. The lens adjusts to focus the light on the retina, where it appears upside down and backward. Receptor cells on the retina are excited or inhibited by the light and send information to the visual cortex through the optic nerve.
The retina has two types of photoreceptor cells: rods, which detect brightness and respond to black and white, and cones, which respond to red, green, and blue. Colour blindness occurs when people lack function in the red- or green-sensitive cones.
Feature detector neurons in the visual cortex help us recognize objects, and some neurons respond selectively to faces and other body parts.
The Young-Helmholtz trichromatic colour theory proposes that colour perception is the result of the signals sent by the three types of cones, whereas the opponent-process colour theory proposes that we perceive colour as three sets of opponent colours: red-green, yellow-blue, and white-black.
The ability to perceive depth occurs as the result of binocular and monocular depth cues.
Motion is perceived as a function of the size and brightness of objects. The beta effect and the phi phenomenon are examples of perceived motion.
