Which of the following theories predicts when and how we detect a stimulus amid background noise?

Module 3.1

Sensing Our World: Basic Concepts of Sensation

Sensation

�      Sensation

�  a process by which our sensory receptors and nervous system receive and represent stimulus energy

�      Perception

�  a process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events

Sensation

�      Sensory receptors

�   Eyes

�   Ears

�   Nose

�   Mouth

�   Joints, muscles

�   Skin

Sensation

�      Gustav Theodor Fechner: Elements of Psychophysics (1860)

Absolute and Difference Thresholds

�      Absolute Threshold�

�   minimum stimulation needed to detect a particular stimulus

�   usually defined as the stimulus needed for detection 50% of the time

�      Difference Threshold

�   minimum difference between two stimuli that a subject can detect 50% of the time

�   just noticeable difference (JND)

�   increases with magnitude

Psychophysical Theory

�      Signal Detection Theory

�   predicts how and when we detect the presence of a faint stimulus (signal) amid background stimulation (noise)

�   assumes that there is no single absolute threshold

�   detection depends partly on person�s

�   experience

�   expectations

�   motivation

�   level of fatigue

Absolute and Difference Thresholds

�      Weber�s Law-� to perceive a difference between two stimuli, they must differ by a constant proportion

�   light intensity-� 8%

�   weight-� 2%

�   tone frequency-� 0.3%

�      Sensory adaptation-� diminished sensitivity with constant stimulation

Module 3.2

Vision: Seeing the Light

Seeing the Light

�      Vision

�   Light energy converted to signals the brain interprets to produce experience of sight

�      Light

�   Physical energy, electromagnetic radiation

�   Wavelength corresponds to color

Seeing the Light
The optics of vision

The Eye

�      Parts of the eye

�   Cornea

�   Iris

�   Pupil

�   Lens: accommodation

�   Retina: rods and cones

�   Bipolar cells, ganglion cells

�   Optic nerve (blind spot)

�   Fovea

Parts of the Eye (Figure 3.3)

Visual pathways

Light to Neural Impulses
(Figure 3.5)

Feature Detectors

�      Neurons that respond to specific features of the visual stimulus

�    Within the visual cortex

�    Discovered by Hubel and Wiesel

Color Vision

Negative Afterimages

Color-Deficient Vision

Module 3.3

Hearing: The Music of Sound

Sound Waves

�      Based on vibrations

�      Amplitude

�    Height of wave

�    Decibels

�      Frequency

�    Number of waves per second

�    Pitch

Sound Waves (Figure 3.10)

The Ear

�      Passage of sound waves

�   Outer ear

�   Eardrum

�   Ossicles

�   Oval window

�   Cochlea: basilar membrane, hair cells

�   Auditory nerve

Sound Waves to Neural Impulses
(Figure 3.11)

The cochlea

The Organ of Corti

Perception of Pitch

�      Place theory

�   �Location on basilar membrane determines pitch

�      Frequency theory

�   Basilar membrane vibrates at same frequency as sound wave

�      Volley principle

�   Groups of neurons fire in rotation

Hearing Loss

�      Conduction deafness

�   Damage to middle ear

�      Nerve deafness

�   Damage to hair cells or auditory nerve

Sounds and Decibels (Figure 3.12)

Module 3.4

Our Other Senses: Chemical, Skin, and Body Senses

Olfaction

�      Smell

�      Chemical molecules

�   Specific smells depend on shape

�      Nose, olfactory nerve, olfactory bulb

�      Important for food flavor

�      Pheromones

Skin Senses

Pain

�      Receptors in

�   Skin, muscles, joints, ligaments, teeth

�      Gate-control theory of pain

�   Mechanism in spinal cord controls pain messages

�   Bottleneck may block pain

�   Role of endorphins

�   Acupuncture

Kinesthesis

�      Receptors in joints, ligaments, muscles

�      Information about

�   Movement of body parts

�   Relative positive of body parts

�      Allows for automatic movements

Vestibular Sense

Module 3.5

Perceiving Our World: Principles of Perception

Perception

Process by which the brain interprets sensations, turning them into meaningful representations of the world

Attention

�      First step in perception

�      Selective attention

�      Influenced by

�   Motivational states

�   Repeated exposure

�   Increased attention

�   Habituation

Perceptual Set

Letter B or Number 13?
�(Figure 3.18)

Visual Processing

�      Bottom-up processing

�   Focus on specific shapes, individual features

�      Top-down processing

�   Experience and knowledge shape perception

Gestalt Principles

�      Gestalt: �unitary form,� �pattern,� �whole�

�      Laws of perceptual organization

�   Figure and ground

�   Grouping

�   Proximity

�   Similarity

�   Continuity

�   Closure

�   Connectedness

Gestalt Laws of Grouping
(Figure 3.24)

Perceptual Constancies

�      Tendency to perceive an object as remaining the same even when retinal image changes

�      Examples

�   Shape constancy

�   Size constancy

�   Color constancy

�   Brightness constancy

Shape Constancy (Figure 3.25)

Depth Perception

�      Depth Perception

�    ability to see objects in three dimensions

�    allows us to judge distance

Depth Perception

�      Binocular cues

�   retinal disparity

�   images from the two eyes differ

�   closer the object, the larger the disparity

�   convergence

�   neuromuscular cue

�   two eyes move inward for near objects

Depth Perception

�      Monocular Cues

�    relative size

�    smaller image is more distant

�    interposition

�    closer object blocks distant object

�    relative clarity

�    hazy object seen as more distant

�    texture� coarse --> close������������������������ fine --> distant

Illusions

Visual Illusions

�      Examples

�    Muller-Lyer illusion

�    (Carpentered-world hypothesis)

�    Ponzo illusion

�    Impossible figures

�    Moon illusion

�    Apparent movement

�    Stroboscopic movement

�    Phi phenomenon

Visual Illusions (Figure 3.28)

Subliminal Perception

�      Stimuli presented below level of conscious awareness

�      Can it influence attitudes or behavior?

Extrasensory Perception

�      Parapsychology: scientific study of psi and related� phenomena

�      Extrasensory perception (ESP) or psi

�   Telepathy

�   Clairvoyance

�   Precognition

�   Psychokinesis

Extrasensory Perception

Ganzfeld: Homogenous visual field.

Subjects in a ganzfeld experiment

sit in a comfortable chair, have their

eyes covered by ping-pong balls

and hear white noise (i.e., static).

The atmosphere is a relaxed one

and the subject reports any

impressions that he/she is aware

of.

Extrasensory Perception

���� Psi, as demonstrated� under laboratory conditions, appears to be a very weak and unstable phenomenon.� Parapsychologists have had a lot difficulty creating the exact experimental conditions under which acceptable and reliable psi effects can be demonstrated.

Module 3.6

Application: Psychology and Pain Management

Pain Management

�      Distraction

�      Bottleneck at the �gate�

�    Such as rubbing, cold packs

�      Changing thoughts and attitudes

�    Negative pessimistic self-evaluations: more pain

�    Rational alternatives: cope more effectively

�      Accurate information

�      Meditation

�      Biofeedback: electromyographic, thermal

What is noise in signal detection theory?

Which of the following describes the difference between sensation and perception?

What is the detection of stimuli?

What is signal detection theory example in psychology?