AP PSYCHOLOGY UNIT 4

• sensation: A process in which our sensory receptors and nervous system receive and represent stimulus energy (bottom-up processing)

• bottom-up processing: begins with sense receptors and works up to the brain’s integration of sensory information

• top-down processing: information guided by higher-level mental processes, construct perceptions drawing on our experience and expectations

• absolute threshold: minimum stimulation needed to detect a particular stimulus 50% of the time

• difference threshold: minimum difference between two stimuli required for detection 50% of the time (JND)

• signal detection theory:

• predicts how and when we detect the presence of a faint stimulus amid background stimulation

• assumes there is no single absolute threshold

• → experience, expectations, motivation, level of fatigue

• subliminal: when stimuli are below the absolute threshold for conscious awareness (still receiving stimuli)

• Weber’s law: to perceive that two different stimuli differ by a constant minimum percentage

• 1. light intensity 8%

• 2. weight 2%

• 3. tone frequency 0.3% (hearing)

sensory adaptation: diminished sensitivity as a consequence of continuous stimulation.

• transduction: conversion of energy of one form to another; transforming stimulus energy into neural impulses

• wavelength: the distance from the peak of one wave to the peak of the next

• iris: eye colour/muscle is key

• Lens: controls the amount of sunlight that hits the eye

• accommodation: the process by which the eye lens changes shape (leads to near-sightedness, farsightedness, or closer to normal vision)

• acuity: sharpness of vision

• farsighted: far objects are seen more clearly; behind the retina

• nearsided: close objects are seen more clearly; the front of the retina

• retina:

• 1. rods: peripheral retina, detect black, white, and gray; twilight and low light

• 2. cones: near the center of the retina, fine detail, color vision, daylight or well-lit conditions.

  

  1. Light enters the eye, triggers photochemical reactions → 2. chemical reaction in turn activates bipolar cells → 3. bipolar cells activate ganglion cells, the axons converge to form the optic nerve, which transmits information. To the visual cortex in the brain’s occipital lobe.

• 1879 Thomas Edison invented the lightbulb → increase in cones

• blind spot: no receptor cells

• optic nerve: TRANSDUCTION

• fovea: central point in the retina

• transduction: conversion of one form of energy to another

• 1. ^ thalamus

• 2. occipital lobe

• 3. Feature detectors: nerve cells in the brain that respond to specific features. (shape, angles, and movements)

• 4. parallel processing: simultaneous processing of several aspects of a problem.

• 5. Abstraction: Brain’s higher-level cells respond to combined information from feature detector cells

• vision:

• trichromatic theory: Young and Helmholtz (three different retinal receptors).

• Opponent-process theory: opposing retinal processes enable color vision.

• trichromatic → opponent process → after image.

• color constancy: perceiving familiar objects as having consistent color, even if changing illumination alters the wavelengths reflected by the object.

• Audition:

• frequency

• pitch: tone’s highness or lowness, depending on frequency.

• 85 decibels; prolonged exposure to this level or higher will lead to hearing loss.

• hearing (audition)

• place theory: theory that links the pitch we hear with the place where the cochlear membrane is stimulated

• The frequency theory: the rate of nerve impulses traveling up the auditory nerve matches the frequency of a tone, thus enabling us to sense its pitch.

• Hearing loss:

• 1. equipment

perception: a process in organizing and interpreting sensory information, enabling us to recognize objects and events (top-down processing)

• selective attention: focus of conscious awareness on a particular stimulus

• ^ change blindness (lack of selective attention)

• visual capture: tendency for vision to dominate other senses

• gestalt: tendency to integrate pieces of information into meaningful wholes

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

• Depth perception: how human beings perceive depth

• 1. binocular cues:

• (a) retinal disparity

• Images from the two eyes differ

• closer to the object, the larger the disparity

• (b) convergence

• The two eyes move inward for a near object

• 2. monocular cues

1. relative size: the smaller image is more distant

2. interposition: a closer object blocks the distant object

3. relative clarity: hazy object seen as more distant

4. texture: coarse → close | fine → distant

5. relative brightness: closer objects appear higher

6. linear perspective: parallel lines converge with distance

7. Relative height: higher objects are seen as more distant

8. relative motion: closer objects seem to move faster

——————————————————————————————————————-

• Perceptual constancy: perceiving objects as unchanging even as illumination and retinal image change (color, shape, size)

• Perceptual adaptation: the ability to adjust to an artificially displaced visual field

• Perceptual set (developed based on our environment/exposure): a mental predisposition to perceive one thing and not another.

• ex: bus oil story

• Human Factors Psychology: explores how people and machines interact, and explores how machines and physical environments can be adapted to human behaviors.

• Extra-sensory perception: a controversial claim that our perception can occur apart from sensory input

• parapsychology: the study of paranormal phenomena

1. ESP

2. Psychokinesis