Psychology Unit V: Sensation & Perception

SENSATION & PERCEPTION

Sensation

• window into the world
• process by which our sensory receptors and nervous system receive stimulus from the environment 
• processing of stimuli

Perception

• interpret what comes into window
• essentially an interpretation and elaboration of sensation
• organizing and interpreting sensory information, enabling us to recognize meaningful objects and events

Visual Capture

• tendency for vision to dominate other senses

Gestalt Psychology

• "means an organized whole"
• these psychologists emphasize our tendency to integrate pieces of info into meaningful wholes

Gestalt Philosophy

• whole is greater than the sum of its parts

Figure - Ground Relationship

• the organization of the visual field into objects (figures) that stand out from their surroundings (ground)

Grouping

• perceptual tendency to organize stimuli into groups that we understand

1. Proximity: nearby objects together
2. Similarity: similar figures together
3. Continuity: continuous patterns together
4. Connectedness: uniform & linked figures group together

Depth Perception

• ability to see objects in 3D although images that strike the retina are 2D
• allows us to judge distance

Binocular Cues

• depth cues that depend on two eyes
• Retinal Disparity: binocular cue for seeing depth
• the closer an object come to you the greater the disparity is between two images

Monocular Cues

• depth cues that depend on one eye
• Interposition: if something is blocking our view, we perceive it as closer 
• Relative Size: if we know two objects are similar in size, the one that looks smaller is further away
• Relative Clarity: we assume hazy objects are farther away

1. Texture Gradient: the coarser it is, the closer it is
2. Relative Height: things higher in our field of vision, look farther away
3. Relative Motion: things closer look like the move more quickly
4. Linear Perspective: parallel lines seem to converge at a distance
5. Light & Shadow: dimmer objects appear farther away because they reflect less light

Phi Phenomenon

• illusion of movement created when two or more adjacent lights blink on and off in succession

Perceptual Consistency

• perceiving objects as unchanging even as illumination and retinal images change

Sensation & Perception

Bottom Up vs. Top Down Processing

• Bottom Up: analysis that begins with the sense receptors and works up to the brain's integration of sensory information
• Top Down: information processing guided by higher - level mental processes, when we construct perceptions drawing on our experience and expectations

Absolute Threshold

• minimum stimulation needed to detect a stimulus 50% of the time

Difference Threshold

• the difference that a person can detect between two stimuli 
• aka: Just Noticeable Difference

Weber's Law

• idea that to perceive a difference between two stimuli, they must differ by a constant percentage , not a constant amount. 

Signal Detection Theory

• predicts how we detect a stimulus amid other stimuli
• assumes that we do not have an absolute threshold
• we detect stuff based on experience, motivation, and fatigue level.

Subliminal Stimulation

• below one's absolute threshold for conscious awareness

Transduction

• transforming signals into neural impulses 
• information goes from the senses to the thalamus, then to various areas of the brain

Sensory Adaptation

• diminished sensitivity as a result of constant stimulation

Selective Attention

• focusing of conscious awareness on a particular stimuli

Cocktail Party Effect

• ability to listen to one voice among many

Pheromones

• chemical messengers that are picked up through our sense of smell

Touch

• receptors located in skin
• Gate Control Theory of Pain: where nervous system blocks or allows pain signals to pass to the brain

Vestibular Sense

• tells where the body is oriented in space
• sense of balance

Kinesthetic Sense

• tells where body parts are 
• receptors located in muscles and joints

Vision

Transduction

• conversion of one form of energy to another

Wavelength

• distance from the peak of one light wave to the peak of the next
• distance determines the hue (color) of the light we perceive

Intensity

• amount of energy in a light wave 
• determined by height of a wave
• the higher the wave, the more intense light is

Parallel Processing

• processing of several aspects of a problem simultaneously 

Young Helmholtz Trichromatic Theory

• three color theory
• realized that any color can be created by combining the light waves of three colors (primary) 
• red, green, and blue
• most color blind people lack cone receptor cells for one or more primary colors

Rods

• facilitate black & white vision

Cones

• facilitate color vision

Opponent Process Theory

• we can't see certain colors together in a combination

Hearing (Audition)

Frequency

• number of complete wavelengths that pass through a point at a given time
• determines pitch of a sound

Amplitude

• how loud the sound is
• the higher the crest of the wave is, the louder the sound is
• measured in decibels

Helmholtz's Place Theory

• we hear different pitches because different sound waves trigger activity at different places
• along the cochlea's basilar membrane 

Frequency Theory

• we sense pitch by the basilar membrane vibrating at the same rate as the sound

Hearing Loss

• Conduction: caused by damage to the mechanical system of ear
• Sensorineural: damage to cochlea's receptor cells or to auditory nerves

Smell & Taste

• chemical senses

Sensory Interaction

• the principle that one's senses many influence another

Papillae 

• those bumps on our tongue
• help grip food while chewing
• contain taste buds