Sensation and perception

Sensation

Process by which stimulated receptor creates pattern of neural messages that represent stimulus of brain

Perception

Process that elaborates and assigns meaning to incoming sensory patterns

All our sense organs…

Transform physical stimulation into neural impulses

Relationship between sensation and perception

Perception is elaboration of sensation

Bottom up processing

Analysis of stimulus begins with sense receptors then works up to level of brain

Top down processing

Higher level mental processes

Perceptual set

Perceive one thing and not another due to top down processes

Cocktail party effect

Shows selective selection

Inattentional business

We miss obvious things in background because we aren’t attending to them

Change blindness

Stimulus undergoes change without being noticed by its observer

Absolute threshold

Minimum simulation needed to detect particular stimulus 50% of time

Subliminal threshold

Stimuli below absolute threshold

Just Noticeable Difference

Minimal amount of change in signal that is stlil recognized

Weber’s law

To perceive as different, two stimuli must differ by a constant minimum percentage

SDT

Predicts how and when we detect presence of signal amid background noise. Depends on PEML

PEML

Person’s experience, expectations, motivation, level of fatigue

Priming

Unconscious activation of certain associations

Sensory adaptation

Way our senses adjust to different stimuli

Habituation

Diminishing of response to frequently repeated stimulus

Transduction

Converting stimulation into neural messages

Why are our senses all alike?

They go through transduction, they are more sensitive to change, they provide us with info about environment

The eye…

transduces light into neural signals which happens in retina

Hue

Color determined by wavelength of light

Short wavelength has…

bluish colors and high pitched sounds

Intensity

Amount of energy in wave determined by amplitude

Small amplitude has…

dull colors and soft sounds

Cornea

outer covering of eye

Pupil

black part of eye

Iris

forms color portion of eye

Lens

structure behind pupil that changes shape to help focus images on retina

Acuity

sharpness of vision

Retina

light sensitive inner surface of eye

Blind spot

The point which optic nerve leaves the eye

Fovea

central focal point in retina

Optic nerve

nerve causing neural impulses from eye to brain

Order of eye

Rods and cones, bipolar cells, ganglion, optic nerve

Ganglion cells

Neurons that connect to bipolar cells

Bipolar cells

Neurons that connects rods and cones to ganglion cells

Optic chasm

Point in brain where optic nerves meet

Visual pathway

Half of optic nerves cross into LGN in thalamus into visual cortex

Feature detectors

Nerve cells in brain that respond to specific features

Trichromatic theory

Retina contains three receptors sensitive to RGB colors

Opponent process theory

Processing four primary colors in pairs

The Gestalt Theory

Whole of anything is greater than its parts

Figure ground

Differentiating object from background

Grouping and proximity

We put things closer together as groups

Grouping and continuity

We group things that we associate with each other

Law of Pragnanz

We see simplest organization requiring least cognitive effort

Retinal disparity

Image from two eyes differ

Convergence

Eyes move inward to see near objects

Relative size

Closer objects are larger

Interposition

Something in front is closer

Linear perspective

Lines converge in distance

Relative motion

Objects near you appear to move quickly

Texture gradiant

More texture when closer

Color constancy

Perceiving colors as constant no matter lighting

Size constancy

Perceive objects as constant size no matter distance

Sensory deprivation

Reduction of senses

Perceptual adaptation

Adapting to environment by filtering out distractions

Hearing

vibrational energy of vibrating objects

Process of hearing

Transmits ear vibrations to cochlea causing oval window to vibrate causing ripples in hair cells which triggers impulses in nerve fibers

Place theory

links pitch with place cochlea’s membrane is stimulated

Frequency theory

brain identifies pitch of sounds according to how rapidly nerve impulses fire

Conduction deafness

Inability to hear from damage of structures

Nerve deafness

Inability to hear from deficit of transmitting impulses from cochlea to brain

Vestibular sense

Sense of balance

Kinesthetic sense

Sense of position and movement in body

Olfaction

Sense of smell

Ansomia

loss of smell

Pheromones

odors that send messages to other species

Process of smell

interact with nose hairs which convey info to brain’s olfactory bulbs

Gustation

sense of taste

Five taste qualities

Sweet, sour, bitter, salty, umami

Skin sensitivity…

Depends on number of receptors in each area

Touch localization…

depends on lengths of pathways from simulated parts to brain

Gate control theory

spinal cord contains gate that blocks pain signals or passes them to brain

Synesthesia

experiencing one sense in terms of another

Motivation

Process in starting activities

Instinct theory

Theory that all behaviors are determined by innate factors and biologically based behaviors

Drive reduction theory

Idea that psychological need creates state of tension motivating people to satisfy their needs. Theory aims for homeostasis

Arousal theory

Human motivation aims to seek levels of arousal

Yerkes dodson law

There is an optimal level of arousal for best performance of any task. More complex the task the lower the arousal

Hierarchy of needs theory (Maslow)

Certain needs have priority over others

Criticisms of Maslow

People neglect basic needs for more social needs, cultures see needs differently

Physiology of hunger

Stomach contractions send signals to brain making us aware of hunger

Lateral hypothalamus

Triggers hunger

When glucose levels are low…

signals brain you need to eat

Insulin

hormone diminishing blood sugar

Ghrelin

hormone increasing blood sugar

Set point theory

Point which individual’s weight is set where an increase in hunger acts to restore lost weight

Basal metabolic rate

When we starve this drops

What motivates sexual behavior?

Necessary for survival of species

Physiological response cycle

Excitement, plateau, orgasm, resolution

Alfred Kinsey

research on male and female sexual behavior

Sexual orientation

persons preference for emotional and sexual relationship

Social acceptance

A sense of belonging with others increases self esteem

Ostracism

Social exclusion leads to bad symptoms

Fortifying health

People who have close friends are healthier

Achievement motivation

A desire for significant accomplishment

Extrinsic motivation

Motivation through punishments and rewards