Sensation and Perception Flashcards
Psychophysics
The study of the relationship between physical energy and psychological experiences.
Stimulus
A change in the environment that can be detected by sensory receptors.
Absolute Threshold
The weakest level of a stimulus that can be correctly detected at least half of the time.
Signal Detection Theory
Maintains that minimum threshold varies with fatigue, attention, expectations, motivation, emotional distress, and from one person to another.
Difference Threshold
Minimum difference between any two stimuli that a person can detect 50% of the time.
Just Noticeable Difference (JND)
Experience of the difference threshold.
Weber’s Law
Difference thresholds increase in proportion to the size of the stimulus.
Subliminal Stimulation
Receiving messages below one’s absolute threshold for conscious awareness.
Transduction
Transformation of stimulus energy to the electrochemical energy of neural impulses.
Perception
The process of selecting, organizing, and interpreting sensations, enabling you to recognize meaningful objects and events.
Cornea
Transparent, curved layer in the front of the eye that bends incoming light rays.
Iris
Colored muscle surrounding the pupil that relegates the size of the pupil opening.
Pupil
Small adjustable opening in the iris that is smaller in bright light and larger in darkness.
Lens
Structure behind the pupil that changes shape, becoming more spherical or flatter to focus incoming Rays into an image on the light-sensitive retina.
Accommodation
Process of changing the curvature of the lens to focus light rays on the retina.
Retina
Light sensitive surface in the back of the eye containing rods and cones that transducer light energy. Also has layers of bipolar cells and ganglion cells that transmit visual info to the brain.
Fovea
Small area of the retina in the most direct line of sight where cones are most concentrated for highest visual activity in bright light.
Photoreceptors
Modified neurons that convert light energy to electrochemical neural impulses.
Rods
Photoreceptors that detect black, white, and gray and that detect movement. Necessary for peripheral and dim-light vision when cones do not respond. Distributed throughout the retina but not in the fovea.
Cones
Photoreceptors that detect color and fine detail in daylight or in bright light conditions. Most concentrated in the fovea of the retina; none in the periphery.
Bipolar Cells
Second layer of neurons in the retina that transmit impulses from rods and cones to ganglion cells.
Ganglion Cells
Third layer of neurons in the retina, whose axons converge to form the optic nerve.
Blind spot
Region of the retina where the optic nerve leaves the eye so there are no receptor cells; creates an area with no vision.
Optic Nerve
Nerve formed by ganglion cell axons; carries the neural impulses from the eye to the thalamus.