WHAT ARE 6 FEATURES OF PERCEPTION? • *knowledge-based - we interpret sensations based on what we already know; • *inferential- we form perceptual hypotheses based on incomplete information; • *categorical- put sensations in categories based on common features;
6 Features of Perception (continued) • *relational- features can be related in a consistent, coherent way; • *adaptive- allows focusing on most important information to handle a situation; • *automatic-does not depend on necessarily on conscious processes
2. WHAT ARE 2 APPROACHES TO PERCEPTION? • *constructionist- emphasizes knowledge basis and inferential character of perception; • *ecological- source of information sensed directly from the environment; incoming stimuli give necessary information.
3. WHAT ARE 2 PRINCIPLES OF PERCEPTION? • *figure/ground: figure has meaning, stands out, seems to be in front, and has contours or edges; ground is meaningless, shapeless and seems to be in back of the figure. • *grouping: includes proximity or closeness, similarity, continuity, closure, orientation, simplicity.
4. WHAT ARE 4 ASPECTS OF PERCEPTUAL CONSTANCY? • *definition: objects seem to remain constant in size, shape and color regardless of changing retinal image. • *size constancy: we believe objects stay the same size even though their images on the retina get bigger or smaller
Perceptual constancy • *shape constancy: objects are seen as being the same shape regardless of changing shape of retinal image. • *color constancy: perceived color stays the same regardless of amount of light shining on it.
5. WHAT ARE 3 ASPECTS OF DEPTH PERCEPTION? • *definition: interpretation of how close or far away an object is; allows perceiving the world in 3 dimensions.
Aspects of depth perception (continued) • *6 stimulus cues: include • relative size, • height in visualfield, .
Stimulus cues… • interposition, • linear perspective, • reduced clarity, • light and shadow
Aspects of depth perception (continued) • *3 properties of visual system: accommodation (eye muscles tighten or relax to focus visual image); • convergence (rotation of eyes inward or outward to focus on close object); • binocular disparity (difference between retinal images as in view master example)
6. WHAT ARE 3 ASPECTS OF PERCEIVED MOTION? • *looming: rapid expansion in size of retinal image, filling available space on the retina. • *movement gradient: objects appear to move away from horizon as you move forward. • *info from vestibular and tactile senses: when accelerate in a car, sense pressure from back of seat + head tilts back.
7.WHAT ARE 4 ASPECTS OF PERCEPTUAL ILLUSIONS? • *definition: distorted or false perceptions of reality. • *stroboscopic motion: series of images each slightly different, presented quickly one after the other give the illusion of motion; • movies, for example.
Perceptual Illusions (continued) • *induced motion: • when there is relative motion in figure and ground, we perceive motion in the figure; • example: moon and clouds (small image of moon and large cloud image; • moon perceived as figure and seems to be moving).
Perceptual Illusions (continued) • *distortions of shape: Poggendorf (diagonal line intersect vertical or horizontal lines);
Perceptual illusions (continued) • Ebbinghaus (small circle surrounded by large circles seems smaller than same size circle surrounded by small circles; dieter example);
Perceptual illusions (continued) • Ponzo (two horizontal lines between two converging lines seem to be different in length even though they are actually the same length because of linear perspective).
8. TOP DOWN PROCESSING AND BOTTOM UP PROCESSING IN PERCEPTION • *top down: guided by higher level cognitive processes and by psychological factors; • shows effect of motivation and expectation;
Top down and bottom up processing (continued) • *bottom up: depends on information from stimulus to brain by way of senses • (inspect abstract painting;
Top down and bottom up processing (continued) • listen to unfamiliar language)
9. WHAT ARE 2 FACTORS INFLUENCING TOP DOWN PROCESSING? • *expectancy: context of stimulus creates expectation; • can bias perception by creating a perceptual set; can make recognition easier.
Factors affecting top-down processing (continued) • *motivation: for example, if hungry more likely to see eating places; • influences perception and recognition.
INTRODUCTORY PSYCHOLOGY – CHAPTER 9 CONSCIOUSNESS
1. WHAT IS CONSCIOUSNESS? • mental process of being aware of own thoughts, feelings, actions, perceptions; • involves self reference.
2. HOW HAS CONSCIOUSNESS BEEN STUDIED? • subjective: structuralists; • introspection to identify individual sensations; unreliable.
Studying consciousness (continued) • objective: • eeg, additional eeg information • pett, additional pet scan information
Objective measures of consciousness • cat scans; additional cat scan information • records of electrical activity in the brain;
Studying consciousness (continued) • animal responses: to seeing own image in a mirror; • shows consciousness results from social interaction.
3. WHAT ARE 3 LEVELS OF CONSCIOUSNESS? • a)unconscious: totally inaccessible to conscious experience; e.g. blood pressure; • requires special methods such as biofeedback;
Levels of Consciousness (continued) • b)cognitive unconscious/preconscious: not conscious of; • may easily become aware of; • "cocktail party" phenomenon;
Levels of Consciousness (continued) • conscious: what you are presently aware of; • lasts about 3 seconds
4. WHAT ARE FEATURES OF STATES OF CONSCIOUSNESS? • range from deep sleep to alert wakefulness; • may be active or passive;
active: manipulating mental activity; • passive: daydreaming; • may result from natural processes or from choice;
States of Consciousness (continued) • may experience altered states of consciousness
States of consciousness (continued) • 3 possible characteristics: • a)shallow careless, uncritical cognitive processes; • b)changed self/other perception; • weakened self-control or normal inhibition.
5. WHAT ARE FEATURES OF DAYDREAMING? • altered state of consciousness = attention to internal events; • may be fantasy oriented or realistic; • can interfere or may be harmless or helpful [relief from boredom];
why do we daydream: • 1)may be constant/ongoing and become apparent when other mental activity ceases; • 2)may maintain desirable level of activity when stimulation from outside is too low.
6. WHAT ARE ASPECTS OF SLEEP? • stage 0:relaxed, eyes closed, awake, tension in body muscles, normal eye movements, eeg mixed with some alpha; • stage 0-1: slow, rolling eye movements, eeg irregular, increased alpha;
Stages of sleep • stage 2: eeg shows pointed "spindles" + k-complexes; • stage 3: eeg shows spindles + k-complexes + delta waves (slower and stronger than alpha); • stage 4: more than 50% delta waves, deepest sleep.
IN GENERAL: 1 1/2 HOURS FROM STAGE 1 TO STAGE 4. • REM sleep: rapid eye movement or active sleep; • eeg similar to being active and awake;
REM sleep • heart rate, respiration, blood pressure resemble active waking state; • muscle tone decreased almost to paralysis; • 80% awakenings result in reported dreaming.
SINGLE NIGHT'S SLEEP: 4-6 CYCLES through stages 1-4; • each cycle = about 90 min (1 1/2hrs), • first half = mostly deep sleep (stages 3 & 4); • second half = mostly stage 2 and REM
7. WHAT ARE 7 SLEEP DISORDERS? • a)insomnia - problems getting to sleep or staying asleep; • results in fatigue during the day; • related to mental distress, including depression and anxiety;
Insomnia treatment: • temporary and dangerous/sleeping pills and alcohol; • more effective: • biofeedback, relaxation training, stress management, psychotherapy, associate bed with sleeping, avoid caffeine; .
(b) hypersomnia: • sleep longer than is necessary; • fatigue; • daytime naps may contribute to this problem;
(c) narcolepsy: • experience sudden switch into several minutes of REM sleep; • decreased muscle tone; • may collapse; • naps may help;
(d) nightmares: • frightening dreams; • sometimes recurring;
(e) night terrors: • occur in quiet (non-REM) sleep; • may be associated with frightening dreams; • may result in wakening into state of intense fear;
(f) sleep-walking: • mostly starts in non-REM sleep; • especially stage 4; • usually not remembered;