Psychology A Concise Introduction Chapter 3

Volley principle

Cells taking turns firing will increase the maximum firing rate for a group of cells.

Additive mixtures

Direct mixtures of different wavelengths of light in which all of the wavelengths reach the retina and are added together.

Contextual effect

The use of the present context of sensory information to determine its meaning.

Complementary colors

Wavelengths of light that when added together produce white.

Retinal disparity

A binocular depth cue referring to the fact that as disparity (difference) between the two retinal images of an object increases, the distance of the object from us decreases.

Subjective contour

A line or shape that is perceived to be present but does not really exist. The brain creates it during perception.

Linear perspective

A monocular depth cue referring to the fact that as parallel lines recede away from us, they appear to converge- the greater the distance, the more they seem to converge. Sometimes referred to as perspective convergence.

Interposition

A monocular depth cue referring to the fact that if one object partially blocks our view from another, we perceive it as closer to us.

Trichromatic theory

A theory of color vision that assumes that there are three types of cones, each only activated by wavelength ranges of light corresponding roughly to blue, green, and red. It further assumes that all of the various colors that we can see are mixtures of various levels of activation of the three types of cones. If all three are equally activated, we see white.

Opponent-process theory

A theory of color vision which assumes that there are three opponent-process cell systems (red-green, blue-yellow, and black-white) that process color information after it has been processed by the cones. The colors in each system oppose one another in that if one color is stimulated, the other is inhibited.

Frequency theory

A theory of pitch perception that assumes that the frequency of the sound wave is mimicked by the firing rate of the entire basilar membrane.

Place theory

A theory of pitch perception which assumes that there is a specific location along the basilar membrane that will maximally respond to a particular frequency, thereby indicating the pitch to the brain. As this location goes down the basilar membrane from the oval window, the pitch goes down from 20,000 Hz to 20 Hz.

Signal detection theory

A theory that assumes that the detection of faint sensory stimuli depends not only upon a person's physiological sensitivity to a stimulus but also upon his decision criterion for detection, which is based on nonsensory factors.

Fovea

A tiny pit in the center of the retina filled with cones.

Nearsightedness

A visual problem in which the light waves from distant objects come into focus in front of the retina, blurring the images of these objects.

Farsightedness

A visual problem in which the light waves from nearby objects come into focus behind the retina, blurring the images of these objects,

Weber's Law

For each type of sensory judgement that we can make, the measured difference threshold is a constant fraction of the standard stimulus value used to measure it. This constant fraction is different for each type of sensory judgement.

Conduction deafness

Hearing loss created by damage to one of the structures in the ear responsible for mechanically conducting the auditory information to the inner ear.

Nerve deafness

Hearing loss created by damage to the hair cells or the auditory nerve fibers in the inner ear.

Subtractive mixtures

Mixtures of wavelengths of light in which some wavelengths are absorbed (subtracted) and so do not get reflected from the mixtures to the retina.

Depth perception

Our ability to perceive the distance of objects from us.

Sensory adaptation

Our sensitivity to unchanging and repetitious stimuli disappears over time.

Cones

Receptor cells in the retina that are principally responsible for bright light and color vision.

Rods

Receptor cells in the retina that are principally responsible for dim light and achromatic vision.

Closure

The Gestalt perceptual organizational principle that the brain completes (closes) incomplete figures to form meaningful objects.

Figure-and-ground principle

The Gestalt perceptual organizational principle that the brain organizes sensory information into a figure or figures (the center of attention) and ground (the less distinct background).

Amplitude

The amount of energy in a wave, it's intensity, which is the height of the wave at its crest.

Top-down processing

The brain's use of knowledge, beliefs, and expectations to interpret sensory information.

Transduction

The conversion of physical energy into neural signals that the brain can understand.

Wave length

The distance in one circle of a wave, from one crest to the next.

Accommodation

The focusing of light waves from objects of different distances directly on retina.

Sensation

The initial information gathering and recoding by the sensory structures.

Perception

The interpretation by the brain of sensory information.

Perceptual set

The interpretation of ambiguous sensory information in terms of how our past experiences have set us to perceive it.

Retina

The light-sensitive layer of the eye that is composed of three layers of cells- ganglion, biopolar, and receptor (rods and cones).

Absolute threshold

The minimum amount of energy in a sensory stimulus detected 50 percent of the time.

Difference threshold

The minimum difference between two sensory stimuli detected 50 percent of the time. The difference threshold is also sometimes referred to as the just noticeable difference, or jnd.

Frequency

The number of times a wave cycles in 1 second.

Steven's power law

The perceived magnitude of a stimulus is equal to its actual physical intensity raised to some constant power. The constant power is different for each type of sensory judgement.

Perceptual constancy

The perceptual stability of the size, shape, brightness, and color for familiar objects seen at varying distances, different angles, and under different lighting conditions.

Dark adaptation

The process by which the rods and cones through internal chemical changes become more and more sensitive to light in dim light conditions.

Bottom-up processing

The processing of incoming sensory information as it travels up from the sensory structures to the brain.

Hair cells

The receptor cells for hearing. They line the basilar membrane inside the cochlea.