psych exam 2

Sensation

Physical process

The experience of having your sense organs stimulated by outer world

Ex: eyes to light, ears to sound

Perception

Psychological process

How your brain interprets objects & events

Interpreting the sensations that are experienced

Example of sensation or perception?

You’re reading your textbook when a noise grabs your attention. When you detected the noise.

Sensation: detecting a stimulus (like hearing a noise)

Not perception: interpreting what that stimulus means (like realizing “oh, that’s a door slamming”)

Example of sensation or perception?

You then realize that it’s the sound of your roommate putting their key in the front door to unlock it. When you identified what the sound was.

Perception: interpreting it as your roommate unlocking the door

Not sensation: detecting (hearing) the sound

Sensory Adaption

When senses become less sensitive to something constant over time

You only notice changes in stimulus

Ex: when you smell something for so long you stop noticing it

Examples of Sensory Adaptions for each sense

• Sight → Walking into a dark room and eventually being able to see better

• Hearing → Not noticing a fan or AC sound after a while

• Smell → Not smelling your perfume after wearing it all day

• Taste → The first bite of food tastes stronger than later bites

• Touch → Not feeling your clothes on your skin after a few minutes

Signal Detection Theory

how we decide whether we notice something or not, especially when it’s hard to tell.

• It explains that detecting something isn’t just about the stimulus

• It also depends on you (attention, expectations, tiredness)

detecting signals in a noisy or uncertain situation.

4 possible responses of a signal detection trial based on the presence or absence of a stimulus.

when signal is present:

• Hit → stimulus is there & you detect it

• Miss → stimulus is there but you don’t detect it

when signal is absent:

• False alarm → stimulus is NOT there but you think it is

• Correct rejection → stimulus is NOT there & you correctly ignore it

Psychological factors that affect Signal Detection

Influence whether stimulus is detected:

• Attention: focused vs distracted

• Expectations: you think something will happen

• Motivation: how important it is to notice it

• Fatigue: tired = worse detection

• Experience: practice makes you better at noticing

Ex: Someone expecting a phone call is more likely to notice the vibration

Absolute Threshold

The smallest amount of a stimulus a person can detect 50% of the time

Involves perceiving or not perceiving a stimulus

Ex: a sound so faint it is only heard half the time.

Difference Threshold

The smallest amount of change between two stimuli that a person can detect 50% of the time

Involves perceiving whether a stimulus changes

Ex: you notice when someone adds a little more weight to your backpack

Absolute Threshold vs Difference Threshold

Absolute = Can I detect it at all?

Difference = Can I notice a change?

Function of Pupil

Opening in the iris that lets light enter the eye

Grows if your interested in something

Affected by drugs, fight, or flight

Function of Iris

The colored part that controls pupil size

Which controls the amount of light entering eye

Function of Cornea

Transparent film that covers your eye

Hard covering that protects the lens

Bends light as it enters in order to focus it

Function of Lens