Introduction to: Sensation and Perception

Introduction to: Sensation and Perception Advanced Placement Psychology Mrs. Kerri Hennen

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Sensation: • The process by which our sensory receptors and nervous system receive stimulus from the environment. • In other words: the process of bringing information from the outside world into the body and brain.

Perception: • The process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events. • Or, the active process of selecting, organizing, and interpreting information brought to the brain by the senses.

How do they work together? • Sensation occurs: • Sensory organs absorb energy from a physical stimulus in the environment. • Sensory receptors convert this energy into neural impulses and send them to the brain. • Perception follows: • The brain organizes the information and translates it into something meaningful.

Bottom-Up vs. Top-Down Processing Top-down processing: • Information processing that begins in higher brain centers and proceeds to sensory receptors. Bottom-up processing: • Information processing that begins at the receptor level and continues to higher brain centers.

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.

Attention, not your attention. :) • Attention is: • the process in which consciousness is focused on particular stimuli. • There’s two types: • Selective Attention • Divided Attention

Selective Attention • The focusing of conscious awareness on a particular stimulus.

An example of selective attention is: Cocktail Part Effect: ability to listen to one voice among many.

Sensory Adaptation • A decline in receptor activity when stimuli are unchanging • Diminished sensitivity as a result of constant stimulation.

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

Habituation • Decline in sensory sensitivity at the neural level due to repeated stimulation. • Different from sensory adaptation because • Simplest form of learning, and is the behavioral equivalent of an animal realizing that a stimulus is irrelevant.

Measuring this: • THRESHOLDS!

Absolute Threshold • The point at which stimulation is detected a 50% of the time. • In other words, given a particular stimulus, it’s the minimum stimulation needed for detection.

Difference Threshold: • The minimum difference that a person can detect between two stimuli 50% of the time. • Also known as Just Noticeable Difference (JND)

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.

Signal Detection Theory: • Predicts how we detect a stimulus amid other stimuli. Signal Detection Theory

Subliminal Stimulation: • Below one’s absolute threshold for conscious awareness. • Show clip Does this work?

We do not perceive the world how it really is, but as it is useful for us to perceive it.

Introduction to: Sensation and Perception