Unit 4

Sensation: The process that occurs when special receptors on the sensory organs are activated, allowing various forms of outside stimuli to become neural signals in the brain.

Perception: The method by which the sensations experienced at any given moment are interpreted and organized meaningfully.

Bottom-up Processing: The analysis of the smaller features to build up to a complete perception. We take in information through the senses and then process it in the brain’s association areas.

Top-down Processing: Using pre-existing knowledge to organize individual features into a unified whole. Using our experience, knowledge, and memory to make meaning out of sensory input.

Selective Attention: The focus of conscious awareness on a particular stimulus excluding other sensory information.

Inattentional Blindness: Failure to see objects when our attention is focused elsewhere.

Change Blindness: We don't notice changes after interruptions to the visual field.

Transduction: In sensation, the transforming of stimulus energies, such as sights, sounds, and smells into neural impulses our brains can interpret.

Psychophysics: The study of how physical energy relates to our psychological experience.

Absolute Threshold: The smallest level of energy required by an external stimulus to be detectable by the human senses, including vision, hearing, taste, smell, and touch.

Signal Detection Theory: The detection of a stimulus depends on both the intensity of the stimulus and the physical/psychological state of the individual.

Subliminal: Stimulus that falls below the absolute threshold for conscious awareness.

Priming: Unconscious activation of associations, predisposing one’s perception, memory, or response.

Difference Threshold: The minimum difference between two stimuli required for detection 50% of the time.

Gustav Fechner: German scientist and philosopher who studied our awareness of faint stimuli and labeled them absolute thresholds. He established a new branch of psychology called psychophysics.

Ernst Weber: Developed what is known as Weber’s Law.

Weber’s Law: Rather than a constant, absolute amount of change, there must be a constant percentage change for two stimuli to be perceived as different.

Sensory Adaptation: A reduction in sensitivity to a stimulus after constant exposure to it.

Perceptual Set: A mental predisposition to see things a certain way.

ESP (Extra Sensory Perception)

Parapsychology: The study of paranormal phenomena.

Wavelength: The distance from the peak of one light or sound wave to the peak of the next.

Hue: With visible light, wavelength determines hue or color.

Intensity: The strength or magnitude of a stimulus.

Pupil: Adjustable opening that allows light to enter the eye.

Iris: Colored part of the eye that controls pupil size.

Lens: Focuses the image onto the retina by changing its curvature (accommodation).

Retina: The light-sensitive inner surface of the eye that contains the receptor rods and cones that process visual information.

Accommodation: Adaptation in which a child or adult develops new schema or modifies existing ones to accommodate new information different from what is already known.

Rods: Detect black, white, and gray, necessary for peripheral vision. Operates in low light conditions.

Cones: In the retina's center, cones provide fine detail and color. Do not operate in low light conditions.

Optic Nerve: Carries visual information to the brain.

Blind Spot: Point where the optic nerve leaves the eye. No rods or cones are located here.

Fovea: Central focal point in the retina. Rods and cones cluster here.

Feature Detectors: Specialized neurons in the visual cortex that respond to specific features of stimuli, such as edges, angles, or motion.

David Hubel: Demonstrated that neurons in the occipital lobe’s visual cortex receive information from individual ganglion cells in the retina (Feature detector cells).

Torsten Wiesel: Discovered feature detector groups of neurons in the visual cortex that respond to different types of visual images.

Parallel Processing: We process various aspects of visual stimulus such as color, depth, movement, and form, simultaneously.

Young-Helmholtz Trichromatic Theory: The retina contains different receptors (cones) each sensitive to a different color.

Opponent-Process Theory: One emotion elicits a feeling of the opposite emotion.

Gestalt: An organized whole. Gestalt psychologists emphasized our tendency to integrate pieces of information into a meaningful whole.

Figure-Ground: We first determine what part of the image is the relevant object or figure and what is the background.

Grouping: We are wired to make sense of visual stimuli by grouping.

Proximity: Nearness

Similarity: Likeness

Continuity: Smooth patterns

Connectedness: We perceive a link between uniform nearby objects.

Depth Perception: The ability to see objects in three dimensions although the images that strike the retina are two dimensional.

Visual Cliff: A research method used to study depth perception in infants and animals.

Binocular Cues: Visual information taken in by two eyes that enable a sense of depth perception, or stereopsis.

Retinal Disparity: We note the difference between the images detected in each eye and use the information to calculate distance.

Monocular Cues: Depth cues that can be perceived by one eye alone:

Relative Size: Closer objects appear larger.

Interposition: Closer objects block the view of objects further away.

Relative Clarity: Closer objects appear more clearly.

Texture Gradient: Texture is coarser and more detailed up close.

Relative Height: Objects higher in our visual field are perceived as farther away, and objects lower in our visual field as closer.

Relative Motion: As we move, stationary objects seem to move with us. Objects nearer than the fixation point move backward. Objects beyond the fixation point move with you.

Linear Perspective: Parallel lines appear to converge as they move into the distance.

Light and Shadow: Nearby objects reflect more light so dimmer objects seem farther away.

Phi Phenomenon: The illusion of movement created when neighboring lights blink on and off in rapid succession.

Perceptual Constancy: We perceive objects as being unchanging even if our sensation of the object changes. Constancies apply to light, color, shape, and size.

Perceptual Adaptation: The brain’s ability to adjust and adapt to changes in sensory input over time.

Color Constancy: We understand that objects have a constant color, even when light conditions change their color.

Audition: The ability of an organism to sense sound and to process and interpret the sensations to gain information about the source and nature of the sound.

Frequency: The number of cycles per second.

Pitch: How high or low a sound is. It is determined by frequency.

Middle Ear: The space between the eardrum and the inner ear.

Inner Ear: Snail-shaped spiral structure in the inner ear, filled with fluid and contains receptors for hearing.

Cochlea: Where the physical stimuli of the sound wave are converted into a neural impulse.

Sensorineural Hearing Loss: Caused by damage to the cochlea’s receptor cells or to the auditory nerve.

Conduction: Caused by damage to the mechanical system that conducts sound waves to the cochlea.

Cochlear Implant: A device for converting sounds into electrical signals and stimulating the auditory nerve through electrodes threaded into the cochlea.

Place Theory: Suggests that we hear different pitches because cells are stimulated on different areas of the cochlea.

Frequency Theory: The membrane vibrates at the same frequency as the sound wave converting info about pitch.

Gate Control Theory: Theorizes that the spinal cord contains small, pain-carrying nerve fibers and larger fibers that conduct other sensory information.

Chemical Senses (Olfaction and Gustatory): Both have sensory receptors that respond to molecules in the food we eat or in the air we breathe.

Kinesthesia: Our sense of body position and movement.

Vestibular Sense: The sense of body movement and position. Provides a sense of balance.

Sensory Interaction: One sense affects the way we experience another.

Embodied Cognition: The influence of bodily sensations, gestures, and other states on cognitive preferences and judgments.