Invitation to Psychology

Chapter 6 Sensation and Perception 223

Perception Without awareness

•   In laboratory studies of subliminal perception,

simple subliminal messages can influence certain

behaviors and judgments, depending on a per-

son’s motivational state (e.g., thirst). However, in

everyday life, there is no evidence that complex

behaviors can be altered by commercial subliminal

recordings.

Psychology in the News, revisited

•   Human perception does not merely capture objec-

tive reality but also reflects our needs, biases, and

beliefs. Our eyes and our ears (and especially our

brains) can play tricks on us—causing us to “see”

things that are not there, such as UFOs, or misin-

terpret what we see.

Taking Psychology With You

•   Years of research have failed to produce convincing

evidence for extrasensory perception (ESP). What

so-called psychics do is no different from what all

good magicians do: capitalize on people’s beliefs,

wishful thinking, and expectations.

• Kinesthesis tells us where our body parts are lo-
cated and equilibrium tells us the orientation of the
body as a whole. Together, these two senses provide
us with a feeling of physical embodiment.

Perceptual Powers: origins

and influences

• Many fundamental perceptual skills are inborn or
are acquired shortly after birth. The visual cliff
studies show that babies have depth perception
by the age of 6 months and probably even earlier.
But without certain experiences during critical
periods early in life, cells in the nervous system
deteriorate, change, or fail to form appropriate
neural pathways, and perception is impaired.
This is why efforts to correct congenital blindness
or deafness are most successful when they take
place early in life.

• Psychological influences on perception include
needs, beliefs, emotions, and expectations (which
produce perceptual sets). Cultures give people
practice with different kinds of perceptual experi-
ences and influence what they attend to.

sensation^187
perception 187

sense receptors^188
anatomical codes 188
doctrine of specific nerve
energies^188
synesthesia 189

functional codes^189
psychophysics 189

absolute threshold^189
difference threshold 190

signal-detection theory^191
sensory adaptation 192

sensory deprivation^192
selective attention 192

inattentional blindness^192
hue 194

brightness^194

saturation 194

retina^194

rods 195

cones^195

dark adaptation 195

bipolar cells^195

ganglion cells 195

optic nerve^196

feature-detector cells 196

trichromatic theory^198

opponent-process theory 198

negative afterimage^199

figure and ground 199

Gestalt principles^199

binocular cues 201

convergence 201

retinal disparity^201

monocular cues^201

perceptual constancy 202

perceptual illusion^202

audition^204

loudness 205

pitch^205

frequency (sound wave)^205

timbre 205

organ of Corti^205

cochlea 205

hair cells 205

cilia^205

basilar membrane 206

auditory nerve 206

echolocation^207

gustation^208

papillae^208

taste buds 208

umami^208

supertasters^209

olfaction 210

gate-control theory 211

phantom pain^212

kinesthesis 213

equilibrium 213

semicircular canals^214

visual cliff^215

critical period 215

perceptual set^217

subliminal perception^218

extrasensory perception

(ESP) 220

Key Terms