Sensation
The process by which stimulation of sensory receptors - the structures in your eyes, ears, and so on - produces neural impulses that represent experiences inside or outside the body
Perceptual Organization
The processes that put sensory information together to give the perception of a coherent scene over the whole visual field
Perception
The processes that organize information in the sensory image and interpret it as having been produced by properties of objects or events in the external, three-dimensional world
Distal Stimulus
In the processes of perception, the physical object in the world, as contrasted with he proximal stimulus, the optical image on the retina
Proximal Stimulus
The optical image on the retina; contrasted with the distal stimulus, the physical object in the world
Absolute Threshold
The minimum amount of physical energy needed to produce a reliable sensory experience; operationally defined as the stimulus level at which a sensory signal is detected half the time
Gustav Fechner
Coined the term psychophysics and provided a set of procedures to related the intensity of a physical stimulus - measured in physical units - to the magnitude of the sensory experience - measured in psychological units
Sensory Adaptation
A phenomenon in which receptor cells lose their power to respond after a period of unchanged stimulation; allows a more rapid reaction to new sources of information
Difference Threshold
The smallest physical difference between two stimuli that can still be recognized as a difference; operationally defined as the point at which the stimuli are recognized as different half of the time
Weber's Law
An assertion that the size of a difference threshold is proportional to the intensity of the standard stimulus
Ernst Weber
Pioneered the study of JNDs or Just noticeable differences
Transduction
Transformation of one form of energy into another; for example, light is transformed into neural impulses
Lens
The flexible tissue that focuses light on the retina
Accommodation
The process by which the ciliary muscles change the thickness of the lens of the eye to permit variable focusing on near and distant objects
Retina
The layer at the back of the eye that contains photoreceptors and converts light energy to neutral responses
Photoreceptors
Receptor cell in the retina that is sensitive to light
Rods
One of the photoreceptors concentrated in the periphery of the retina that are most active in dim illumination; rods do not produce sensation of color
Cones
One of the photoreceptors concentrated in the center of the retina that are responsible for visual experience under normal viewing conditions for all experiences of color
Fovea
Area of the retina that contains densely packed cones and forms the point of sharpest vision
Dark Adaptation
The gradual improvement of the eyes' sensitivity after a shift in illumination from light to near darkness
Blind spot
The region of the retina where the optic nerve leaves the back of the eye; no receptor cells are present in this region
Optic nerve
The axons of the ganglion cells that carry information from the eye toward the brain
Hue
The dimension of color space that captures the qualitative experience of the color of light
Saturation
The dimension of color space that captures the purity and vividness of color sensations
Brightness
The dimension of color space that captures the intensity of light
Sir Thomas Young
Developed the first scientific theory of color vision; suggested that there were three types of color receptors in the normal human eye that produced psychologyically primary sensations: red, green, and blue; Believed that all other colors, he believed, w
Trichomatic Theory
Provided a plausible explanation for people's color sensations and for color blindness (according to the theory, color-blind people had only one or two kinds of receptors).
Hermann von Helmholtz
The man who developed the trichomatic theory and refined sir thomas young's theory
Edwald Hering
Proposed a second theory of color vision in the late 1800s, The opponent-process theory
Opponent-process theory
All color experiences arise from three underlying systems, each of which includes two opponent elements: red versus green, blue versus yellow, or black (no color) versus white (all color). Hering theorized that colors produced complementary afterimages be
Pitch
Sound quality of highness or lowness; primarily dependent on the frequency of the sound wave
Timbre
The dimension of auditory sensation that reflects the complexity of a sound wave
Loudness
A perceptual dimension of sound influenced by the amplitude of a sound wave; sound waves in large amplitudes are generally experienced as loud and those with small amplitudes as soft
Cochlea
The primary organ of hearing; a fluid-filled coiled tube located in the inner ear
Place Theory
The theory that different frequency tones produce maximum activation at different locations along the basilar membrane, with the result that pitch can be coded by the place at which activation occurs
Frequency Theory
The theory that a tone produces a rate of vibration in the basilar membrane equal to its frequency, with the result that pitch can be coded by the frequency of the neural response
Volley Principle
An extnesion of frequency theory, which proposes that when peaks in a sound wave come too frequently for a single neuron to fire at each peak, several neurons fire as a group at the frequency of the stimulus alone
Size Consistency
The ability to perceive the true size of an object despite variations in the size of its retinal image
Shape Consistency
The ability to perceive the true shape of an object despite variations in the shape of the retinal image
Illusions
An experience of a stimulus pattern in a manner that is demonstrably incorrect but shared by others in the same perceptual environment
Bottom-up processing
Perceptual analyses based on the sensory data available in the environment; results of analysis are passed upward toward more abstract representations
Top-down processing
Perceptual processes in which information from an individual's past experience, knowledge, expectations, motivations, and background influence the way a perceived object is interpreted and classified
Ambiguity
Property of perceptual object that may have more than one interpretation
Figure Ambiguity
Multiple interpretations
Figure ground
Background is different, figure has an outline
Illusions
Not the same as hallucinations
Structuralists
Reductionist approach, mentalistic approach (the whole is the sum of its parts)
Cornea
(first structure light passes through heading into the eye) Transparent outer bulge
Iris
(second structure light passes through heading into the eye) Colored muscle
Lens
(third structure light passes through heading into the eye) Accomodation
Retina
(final structure light passes through heading into the eye) Transduction, receptor organ
Rhodopsin
Pigment in the eye that magnifies light
Moon Illusion
Our eyes compensate for the distance between earth and the moon so the moon looks bigger over the horizon than it does overhead when we register how far away it is
Negative afterimage
Perceive a pair of colors
3 pairs of photoreceptors: Red/green, blue/yellow, white/black
Red-Green Blindness
You cannot perceive a certain pair of colors, in this case red-green
Inner Ear
Sound travels by fluid conduction
Oval window and cochlea
Cilia
Mechanoreceptors in the ear
Pure tones
Human ears can sense between 20 and 20,000 Hz; these are considered pure tones
Hertz
One cycle per second is 1 Hz; Shorter waves have higher frequencies
Frequencies
Different frequencies vibrate cilia at different rates not places; accounts for low frequencies (20-300 Hz); Difficulty accounting for high frequencies
Outer ear
Sound travels by air conduction; pinna; ear drum (tympanic membrane)
Middle Ear
Sound travels by bone conduction; Hammer, anvil, stirrup (smallest bones in the body)
Amplitude
Height of a sound wave; measured in decibels (dB); perceived as loudness
Gestalt
Koffka, wertheimer, and kohler; "The whole is greater than the sum of its parts"; Laws of grouping
Law of proximity
Objects that are close together will be perceived as belonging together
Law of closure
We tend to "continue" shapes we know and make them whole again
Law of similarity
Objects that are similar will be perceived as belonging together
Retinal Disparity
Stereopsis; Fusion of signals from disparate points on each retina
Convergence
Eyes more inward for close objects and apart for distant objects (going crosseyed)