Unit 3: Sensation and Perception

Sensation

involves how an organism receives stimuli and info from the surrounding world via sensory organs

Perception

cognitive processes of receiving encoding, storing and organizing sensations

Bottom-up processing

starting with sensory receptors and work up to brain’s integration of sensory information for processing

Topdown processing

Construct perceptions coming from sensations( coming from bottom-up) and on our experiences and expectations

Signal Detection Theory

Ability to identify a stimuli when it is embedded in a distracting background

Psychophysics

study of the links between physical stimuli & psychological experience.

Subliminal Stimulation

Stimulus which is below one’s threshold for conscious awareness.

Difference Threshold

Smallest difference between two stimuli which a subject can detect 50% of the time (Just Noticeable difference)

Weber’s Law

The principle that two stimuli must differ by a constant proportion, not a constant amount, for a difference between them to be detected

Divided Attention

While performing simple motor skills simultaneously, for more cognitively complex tasks, we can only focus on one thing at a time

Stroop effect

recognizes the color of the word first which interferes with our ability to read the word aloud

Selective Attention

The process of directing our awareness to relevant stimuli while ignoring irrelevant stimuli in the environment

Cocktail Party Effect

Being able to focus on what a person says with noise around

Absolute Threshold

the stimulus energy needed to be detected 62% of the time

Inattentional Blindness

Selectively attending to one part of the environment and missing the other

Change Blindness

Specific form inattentional blindness in which we fail to notice changes in our environment

Sensory Adaptation

A reduction in sensitivity to a stimulus after constant exposure to it and is adaptive. Physiological adaptation

Habituation

A kind of learning where your nervous system selectively filters out stimuli. A pattern of decreased response to a stimulus after frequently repeated exposure. Psychological adaptation

Transduction

Conversion of one form of energy to another; receptor cells take incoming energy and change it into neural impulses

Sensory Interaction

Experiments result in two or more senses working together because one sense can influence another

Wavelength

The distance from the peak of one light or sound wave to the peak of the next which determines hue or color for vision

Wave height

Intensity- The amount of energy in a light or sound wave or wave’s amplitude

Cornea

outer portion, bends light to provide focus

Pupil

adjustable opening in the center eye

Iris

A colored ring muscle that controls the size of pupil

Lens

Changes shape to help the eye focus; Accomodation

Retina

A light sensitive surface that contains rods and cones

Bipolar Cells

Receive messages from photoreceptors and transmit them to Ganglion Cells

Ganglion Cells

Converges the Bipolar cells to the optic nerve

Optic Nerve

carries neural impulses to the brain (thalamus)

Fovea

the center focus point

Cones

Far fewer, located in the center of the retina and gives color and light vision

Rods

Far more numerous, located on the periphery of the retina, do not give color vision and give twilight vision

Synesthesia

to perceive together; perceptual phenomenon in which stimulation of one sensory or cognitive pathway leads to involuntary experiences in second sensory or cognitive pathway

Nearsightedness

Objects near are clear; object far away are blurry. Visual image is focused on the front of the retina

Farsightedness

Objects near are blurry; visual image is focuses behind the retina

Normal Vision

Light is focuses directly on the retina

Astigmatism

irregularly shaped cornea, multifocal points

Young-Helmholtz Trichromatic Theory

Retina contains 3 different color receptors; ones most sensitive to red, green, blue.

Opponent Process Theory

Opposing retinal processes enable color vision; so some stimulated by green, but inhibited by red

Feature Detectors

nerve cells in the brain that respond to specific features of the stimulus such as shape, angle or movement

Parallel Processing

Brain processes many aspects simultaneously; divides a visual scene into sub-dimensions.

Color Constancy

Perceiving familiar objects as having consistent color under different conditions of illumination 

Audition

the sense or act of hearing

Wavelength or Frequency:

\# of wavelengths that pass a point in a given time which determines pitch

Pitch

tone’s experienced highness or lowness

Wave height or amplitude

loudness or intensity measured in decibels

Pinna

external part of the ear

Auditory Canal

tube that runs from outer ear to the middle

Eardrum

A tympanic membrane that vibrates with sound waves

Hammer, Anvil, Stirrup

smallest bones; vibrate from the eardrum

Cochlea

coiled, bony, fluid filled tube which sound waves trigger neural impulses and is filled with hair cells

Semicircular Canals

fluid filled tubes to help keep balance; connect to vestibular sacs

Place Theory

links the pitch we hear with the place where the cochlea’s membrane is stimulated

Frequency Theory

the rate of nerve impulses traveling up the auditory nerve matches the frequency of a tone, enabling us to sense its pitch

Congental Deafness

people who are born deaf

Conduction Hearing Loss

caused by the damage to the system that conducts sound waves to the cochlea

Sensorineural Hearing Loss

caused by damage to the cochlea’s receptor cells or to the auditory nerves

Cochlear Implant

A device for converting sounds into electrical signals, to stimulate the auditory nerve into the cochlea

Four distinct skin senses

pressure, warmth, cold and pain

Pain

the way your body tells you that something is wrong

Nociceptors

sensory receptors that detect pain

A Delta Fibers

alarm system; sharp immediate pain

C Fibers

dull, aching pain

Beta Fibers

sense touch

Phantom Limb Pain

some people report strong sensations of pain in missing limb

Gate Control Theory

neurological “gate” in the spinal cord which opens to allow small fibers of pain through but larger fibers can override the small ones to stop pain

Gustatory System

chemical senses which include sweet, salty, sour, bitter umami

Sweet

energy source

Salty

sodium essential to physiological processes

Sour

potentially toxic acid

Bitter

Potential poisons

Umami

proteins to grow and repair tissue

Taste buds

clustered taste cells

Fungiform papillae

Bumps on the tongue where tase buds are located

Processes

1. Molecules enter taste pores of taste buds and stimulate taste cells
2. Nerve impulses travel via the facial nerve or glossopharyngeal nerve to the brain
3. Nerve impulses reaches the thalamus, where it is rerouted to the temporal lobe of the cereberal cortex
4. The taste stimuli is processed by the gustatory cortex

Olfaction

Smell is a chemical sense

Pheromones

Chemical messages sent by another

Smell Process

olfactory receptors => olfactory bulb located below frontal lobe=> olfactory areas in temporal lobes=> limbic system

Kinesthesis

The system for sensing the position and movement of individual body parts

Vestibular

the sense of body movement and position and spatial orientation, including the sense of balance which is located in the inner ear

Perceptual Illusion

when senses conflict, reveal how we organize and interpret sensations and use visual data to help solve this problem

Perceptual Set

A readiness to perceive a stimulus in a particular way

Distal stimuli

stimuli that lie in the distance (that is, outside the body)

Proximal stimuli

the stimulus energies that impinge directly on sensory receptors

Ponzo

the horizontal lines are the same length

**Poggendorff**

 the two diagonal segments lie on the same straight line.

Upside-down T

the vertical and horizontal lines are the same length.

Zollner

the long diagonals are all parallel.

Gestalt

An organized whole where there is a tendency to integrate pieces of information into meaningful wholes

**Figure-ground:**

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

**Grouping**

After distinguishing the figure from the ground, our perception needs to organize the figure into a meaningful form using grouping rules

**Closure**

Although grouping principles usually help us construct reality, they may occasionally lead us astray.

Motion Perception

inferring speed and direction of elements based on input perceived

Stroboscopic Movement

Perceive continuous movement in a rapid series of varying images; aka Phi Phenomenon

Depth Perception

Ability to see objects in three dimensions although the images that strike the retina are two-dimensional and allows us to perceive distance

Convergence

Neuromuscular cue to tell brain the closeness of an object.

Retinal Disparity

Difference between how each retina experiences the world

Relative Height

Vertical dimensions seem longer than identical horizontal

Relative Size

Allows you to determine how close objects are to an object of a known size.