| A | B |
|---|
| Sensation | occurs when sensory receptors and the nervous system receive stimulus energies from our environment |
| Perception | the process that occurs in the brain of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events. |
| Bottom-up processing | analysis that begins with the sensory receptors and works to the brain’s integration of sensory information. |
| Top-down processing | information analysis guided by higher-level mental processes, as when we construct perceptions drawing on our experience and expectations. |
| Selective attention | the focusing of conscious awareness on a particular stimulus. |
| Inattentional blindness | failing to see visible objects |
| Change blindness | failing to notice modifications in the environment |
| Psychophysics | the study of relationships between the physical characteristics of stimuli, such as their intensity, and our psychological experience of them. |
| Absolute threshold | the minimum stimulation necessary to detect a particular stimulus 50% of the time. |
| Signal detection theory | predicts how and when we detect the presence of a faint stimulus amid background stimulation. |
| Subliminal | stimulus below one’s absolute threshold for conscious awareness. |
| Priming | the activation, often unconsciously, of certain associations, thus predisposing one’s perception, memory, or response. |
| Difference threshold | the minimum discrepancy between two stimuli required for detection. |
| Weber’s law | to be perceived as different, two stimuli must differ by a constant percentage (rather than a constant amount). |
| Sensory adaptation | diminished sensitivity as a consequence of constant stimulation. |
| Transduction | transforming of external stimulus energies, such as sights, sounds, and smells into electrical neural impulses our brains can interpret and process; conversion of one form of energy into another. |
| Wavelength | the distance from the peak of one light or sound wave to the peak of the next. |
| Hue | the dimension of color that is determined by the wavelength of light; what we know as the color names blue, green, and so forth. |
| Intensity | the amount of energy in a light or sound wave, which we perceive as brightness or loudness, as determined by the wave’s amplitude. |
| Pupil | the adjustable opening in the center of the eye through which light enters. |
| Iris | a ring of muscle tissue that forms the colored portion of the eye around the pupil and controls the size of the pupil opening. |
| Lens | the transparent structure behind the pupil that changes shape to help focus the images on the retina. |
| Retina | the light-sensitive inner surface of the eye, containing the receptor rods and cones plus layers of neurons that begin the processing of visual information. |
| Accommodation | the process by which the eye’s lens changes shape to focus near or far objects on the retina. |
| Rods | retinal receptors that detect black, white, and gray; necessary for peripheral and twilight vision, when cones don’t respond. |
| Cones | retinal receptor cells that are concentrated near the center of the retina and that function in daylight or in well-lit conditions; detect fine detail and give rise to color sensations. |
| Optic Nerve | carries neural impulses from the eye to the brain. |
| Blind Spot | at the point the optic nerve leaves the eye, there are no receptor cells creating an area where there is not sight |
| Fovea | the central focal point in the retina, around which the eye’s cones cluster. |
| Feature detectors | nerve cells in the brain that respond to specific features of the stimulus, such as shape, angle, or movement. |
| Parallel processing | the analysis of many aspects of a problem simultaneously; the brain’s natural mode of information processing for many functions, including vision. |
| Young-Helmholtz trichromatic theory | the idea that the retina contains three different color receptors – one most sensitive to red, one to green, one to blue – which, when stimulated in combination can produce the perception of any color. |
| Opponent-process theory | the idea that opposing retinal processes (red-green, yellow-blue, white-black) enable color vision. |
