Psychology

Session 9Sensation and Perception

Date: November 4th, 2016

Course instructor: Cherry Chan

Mothercraft College

Agenda

1. Sensation and perception

2. Vision

3. Perceptual organization

4. Sound

5. Smell

6. Taste

7. Touch

What is sensation and

perception?

• Sensation: detecting external stimuli and

sending those stimuli to the brain

• Perception: internal representations of

external stimuli

(Wood, Wood, Boyd, Wood, & Desmarais, 2017)

Sensation and Relaxation • Sensory rooms were first developed for patients

with cognitive impairments, learning disabilities,

dementia, and young children with complex

disabilities.

• Staff and patients have reported an increase

state of relaxation, lower levels of distress, and

psychological and physiological improvements.

(Smith & Jones, 2014)

• Multisensory environment relaxes students and

provides opportunities for students to focus on

particular activities (Stephenson & Carter, 2011)

Signal detection theory

• Detecting a stimulus against a background

“noise” (Wood et al., 2017).

• A signal is detected based on subjective

experience.

• It is a sensory process, depending on the

intensity of the stimulus, and a decision

process, influenced by the individual’s bias (Wade, Tavris, Saucier, & Elias, 2014).

Figure 1. Responses in Signal Detection. Adapted from Psychology (p.194) by C. Wade, C. Tavris, D. Saucier, and L. Elias, 2014.

Sensing without perceiving

• Selective attention: focus on certain

aspects of the environment and block out

others

• Inattentional blindness: unable to

consciously perceive something you are

looking at because you are not paying

attention to it (Wade et al., 2014)

Vision

• Cornea: bending the light towards pupil

• Pupil: opening where light enters eye

• Iris: muscles contract and dilate pupil

• Lens: focus objects onto retina

• Retina: membrane that contains light-

sensitive receptor cells (rods and cones)(Wood et al., 2017)

Figure 2. Major Structures of the Eye. Adapted from Psychology (p.198) by C. Wade, C. Tavris, D. Saucier, and L. Elias, 2014.

Nearsightedness vs

farsightedness

Figure 3. Normal, nearsightedness, and farsightedness. From Normal,

nearsightedness, and farsightedness by Lusby (2013) Retrieved fromhttp://www.nlm.nih.gov/medlineplus/ency/imagepages/19511.htm

Rods and cones

Figure 4. Differences between Rods and Cones. Adapted from Psychology (p.199) by C. Wade, C. Tavris, D. Saucier, and L. Elias, 2014.

Cones

Figure 5. Three types of cones. From Seeing colour by Arizona State

University (2010) Retrieved from http://askabiologist.asu.edu/rods-and-cones

What’s wrong with this child?

Figure 6. Scheibe illusion. From Upside-down optical illusions again by Vurdlak

(2008) Retrieved from http://www.moillusions.com/2008/03/upside-down-

optical-illusion-again.html

Perceptual

organization

Figure 7. Gestalt grouping principles.

From Perception by Diane (2010)

Retrieved from

http://www.rhsmpsychology.com/Ha

ndouts/Gestalt_grouping.htm

Perceptual constancy

• An object has stable properties regardless

of distance, viewing angle, and lighting.

– Size

– Brightness

– Colour

– Shape

(Wood et al., 2017)

Size

Figure 9. In the left panel, the man in the background appears to be about the same height as the

woman in the foreground From Do artists see their retinas? by Perdreau & Cavanagh (2011)

Retrieved from http://c431376.r76.cf2.rackcdn.com/12334/fnhum-05-00171-

HTML/image_m/fnhum-05-00171-g001.jpg

Brightness

Figure 10. Brightness constancy. From Accuracy and inaccuracy in perception by Fong

(2011) Retrieved from

http://students.flatworldknowledge.com/bookhub/10145?e=stangor-ch04_s05

Colour

Figure 11. Colour constancy. From Colour constancy in perception by Gurney

(2010) Retrieved from http://gurneyjourney.blogspot.fr/2010/01/color-

constancy.html

Depth cues

• Binocular depth cues

– Convergence: focusing on nearby objects by

turning eyes inward

– Binocular disparity: differences between two

retinal images

(Wood et al., 2017)

Monocular depth cues

• Interposition: One object blocking the view of another

• Linear perspective: parallel lines come closer

together when they recede into distance

• Relative size: larger objects are closer

• Texture gradient: fuzzy objects are further away

• Atmospheric perspective: blurry and bluish-tint

objects are further away

• Shadow or shading: light creates shadows

• Motion parallax: when you are moving, objects move

in the opposite direction and at different speeds (Wood et al., 2017)

Impossible figures

Figure 12. Elephant feet. From Cognitive illusions by World Mysteries (2011)

Retrieved from http://www.world-mysteries.com/illusions/sci_illusions3.htm

Context and perception

Figure 13. The Cat. From Context effect by Wikipedia (2013) Retrieved from

http://upload.wikimedia.org/wikipedia/commons/3/3a/TheCat.png

Sound• Frequency: the pitch of the sound

• Amplitude: intensity of sound

– A cue for sound distance

• Timbre: sound quality

• Our two ears helps to discern sound

direction

– i.e. sound coming from the right will reach the

right ear a fraction of a second before the left

ear

(Wade et al., 2014; Wood et al., 2017)

Figure 14.Major Structures of the Ear. Adapted from Psychology (p.213) by C. Wade, C. Tavris, D. Saucier, and L. Elias, 2014.

Kinesthetic and vestibular

• Kinesthetic sense: body position

• Vestibular sense: movement

(Wood et al., 2017)

Figure 15. Balance disorder illustration.

From Semicircular canal by

Wikipedia (2013) Retrieved from

http://upload.wikimedia.org/wikipedi

a/commons/3/33/Balance_Disorder

_Illustration_A.png

Smell

Figure 16. Receptors for Smell. Adapted from Psychology (p.218) by C. Wade, C. Tavris, D. Saucier, and L. Elias, 2014.

A Taste Test

Figure 17. Taste Test. Adapted from Psychology (p.217) by C. Wade, C. Tavris, D. Saucier, and L. Elias, 2014.

Touch and pain

• Tactile information is transmitted to the brain

when an object touches and depresses the skin.

• Nerve endings in the skin send signals to the

somatosensory cortex in the parietal lobe.

• Two point threshold: the distance between two

points of stimulation before a person is able to

feel two separate points of contact.

• Endorphins relieve pain and promote positive

mood

(Wood et al., 2017)

ReferencesSmith, S., & Jones, J. (2014). Use of a sensory room on an intensive

care unit. Journal of Psychosocial Nursing and Mental Health

Services, 52(5), 22-30.

Stephenson, J., & Carter, M. (2011). The use of multisensory

environments in schools for students with severe disabilities:

Perception from teachers. Journal of Developmental and Physical

Disabilities, 24(1), 95-109.

Wade, C., Tavris, C., Saucier, D., Elias, L. (2014). Psychology (4th

Canadian ed., DSM-5 Update ed., 4th ed.). Toronto, ON: Pearson

Education Canada.

Wood, S.E., Wood, E.G., Boyd, D., Wood, E., & Desmarais, S. (2017).

The world of psychology (7th Canadian ed). Toronto, ON: Pearson

Canada