Sensation

Sensation

• The process by which our sensory receptors and nervous system receive stimulus from the environment.

Perception

• The process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events.

Bottom-Up v. Top-DownProcessing

NUMBER 70

What if we could sense everything?

Life would hurt.

So we can only take in a window of what is out there.

This is the study of psychophysics: relationship between physical stimuli and our psychological experiences to them.

Absolute Threshold

• The minimum stimulation needed to detect a stimulus 50% of the time.

Difference Threshold• The minimum difference that a person can

detect between two stimuli.• Also known as Just Noticeable Difference

Can you tell the difference?

Weber’s Law• The idea that, to perceive a difference

between two stimuli, they must differ by a constant percentage; not a constant amount.

Just noticeable difference

Just noticeable difference

Just noticeable difference

Just noticeable difference

Just noticeable difference

Just noticeable difference

Just noticeable difference

Just noticeable difference

Just noticeable difference

Just noticeable difference

Just noticeable difference

Just noticeable difference

Just noticeable difference

Signal Detection Theory

• Predicts how we detect a stimulus amid other stimuli.

• Assumes that we do not have an absolute threshold.

• We detect stuff based on our experiences, motivations and fatigue level.

Signal Detection Theory

Subliminal Stimulation

• Below one’s absolute threshold for conscious awareness.

Does this work?Yes and No

•studies showed some emotional reactivity (called priming a response).

•The effects are subtle and fleeting.

Sensory Adaptation

• Diminished sensitivity as a result of constant stimulation.

The concept of sensory adaptation applies to all of our senses.

We do not perceive the world how it really is, but

as it is useful for us to perceive it.

Selective Attention• The focusing of conscious

awareness on a particular stimulus.

An example of selective attention is:

Cocktail Party Effect: ability to listen to one voice among many.

Selective Attention

Selective Inattention

• Inattentional blindness

Selective AttentionSelective Inattention

Change Blindness

Module 17:Influences on Perception

Perceptual Set• Perceptual set

–Mental predisposition

–Schemas

• Perceptual set–Mental predisposition

–Schemas

Perceptual Set

• Perceptual set–Mental predisposition

–Schemas

Perceptual Set

From Leeper, R. W. (1935). A study of a neglected portion of the field of learning: The development of sensory organization. Journal of Genetic Psychology, 46, 41-75. Reprinted by permission of Taylor & Francis Ltd, http://www.tandf.co.uk/journals

Context Effects

• Context effects

Context Effects

Emotion and Motivation

• Motivation on perception

• Emotions on perception

Context Effects

Context Effects