Psych/Soc Deck 2: Sensation, Perception & Consciousness

Sensation

Detection of physical stimuli by sensory receptors.

Example:
Light hits the retina.

Perception

The brain's interpretation of sensory information.

Example:
Recognizing your friend's face.

Sensation vs Perception

Sensation
Receiving information.

Perception
Interpreting information.

Think:

Eyes detect.

Brain decides.

Cornea

First structure that bends (refracts) light.

Provides most of the eye's focusing power.

Pupil

Opening that allows light into the eye.

Iris

Controls pupil size

Lens

Fine-tunes focus by changing shape (accommodation).

Retina

Contains photoreceptors.

Converts light into neural signals.

Fovea

Highest visual acuity.

Mostly cones.

Optic nerve

Carries visual information to the brain.

Blind spot

Location where the optic nerve exits the eye.

No photoreceptors.

Rods

Night vision

Peripheral vision

Motion detection

No color

Cones

Color vision

Daylight

High acuity

Concentrated in the fovea

Outer ear function

Collects sound waves.

Middle ear bones

Malleus

Incus

Stapes

Inner ear

Cochlea

Contains hair cells.

Converts sound into nerve impulses.

Semicircular canals

Balance

Angular acceleration

Mechanoreceptors detect...

Pressure

Touch

Vibration

Stretch

Nociceptors detect...

Pain

Thermoreceptors detect...

Temperature

Olfaction, Which sense bypasses the thalamus?

smell, Smell (olfaction).

Taste receptors detect...

Sweet

Salty

Sour

Bitter

Umami

Bottom-up processing

Starts with sensory input.

Builds toward perception.

Top-down processing

Uses prior knowledge, expectations, and experience to interpret information.

Bottom-up vs Top-down

Bottom-up

Stimulus ➜ Brain

Top-down

Brain ➜ Interpretation

Weber's Law

The just noticeable difference (JND) is a constant proportion of the original stimulus.

→the bigger something already is, the bigger the change needs to be for you to notice it.

Example:
Adding 1 lb to a 5-lb weight is noticeable, but adding 1 lb to a 100-lb weight is not.

Absolute threshold

Minimum stimulus intensity detected 50% of the time.

Difference threshold (JND)

Smallest detectable difference between two stimuli.

Signal Detection Theory

Detection depends on:

• Stimulus strength

• Expectations

• Experience

• Motivation

  • Alertness

False positive

Detecting a signal that is not actually present.

Example:
Thinking your phone vibrated when it didn't.

False negative

Failing to detect a real signal.

Example:
Not hearing your alarm.

Cocktail Party Effect

Ability to focus on one conversation while filtering out others, but still notice personally meaningful stimuli (like hearing your name).

Gestalt Principle

The brain organizes individual parts into meaningful wholes.

→Your brain likes to organize random visual information into simple patterns and groups

"The whole is greater than the sum of its parts."

Closure

Filling in missing pieces to perceive a complete object.

Proximity

Objects close together are perceived as belonging together.

Similarity

Similar objects are grouped together.

Continuity

We prefer smooth, continuous patterns over abrupt changes.

Figure-Ground

Separating an object (figure) from its background.

Circadian rhythm

Approximately 24-hour biological cycle regulated by light and the suprachiasmatic nucleus (SCN).

Melatonin

Hormone released by the pineal gland that promotes sleep.

REM sleep

Dreaming

Rapid eye movements

Muscle paralysis

Memory consolidation

NREM Stage 1

Light sleep.

Theta waves.

NREM Stage 2

Sleep spindles

K-complexes

NREM Stage 3

Deep sleep

Delta waves

Physical restoration

Which sleep stage has delta waves?

NREM Stage 3.

Which sleep stage has vivid dreams?

REM sleep.

Consciousness

Awareness of oneself and the environment.

Selective attention

Focusing on one stimulus while ignoring others.

Divided attention

Attempting to focus on multiple tasks at once.

Usually decreases performance.

Automatic processing

Occurs without conscious awareness.

Example:
Driving a familiar route.

A person recognizes their friend's face after seeing light reflected from them. Which process represents perception?

Recognizing the face (interpreting the sensory input).

A patient loses peripheral vision and night vision. Which photoreceptors are most likely damaged?

Rods

A patient cannot distinguish colors but sees well at night. Which cells are damaged?

Cones

While studying in a coffee shop, you suddenly hear someone say your name. Which phenomenon explains this?

Cocktail party effect

A person expects to see a friend in a crowd and mistakes a stranger for them. Which processing type influenced perception?

Top-down processing.

A subject notices a 2-lb increase when holding a 10-lb weight but not when holding a 100-lb weight. Which law explains this?

Weber's Law.

A participant hears an alarm but thinks it's part of a dream and keeps sleeping. What type of error occurred?

False negative

Someone sees a logo made of incomplete circles but perceives full circles. Which Gestalt principle is demonstrated?

Closure

A patient has damage to the semicircular canals. Which function is most impaired?

Balance and detection of angular acceleration.