What you see is what you get? Heather Johnston March 24, 2005

Cognitive Psychology Wilhelm Wundt - “father of psychology” applied scientific method to human thought and behavior scientific study of thought

Cognitive Psychology How do we learn? How do we remember? How do we use language? How do we perceive the world through our sensory systems?

Sensory Perception Light Visual system “See” my dog Sound waves Auditory System “Hear” my dog barking

Goals of our sensory systems Allows us to effectively interact with objects and events in the environment Minimizes ambiguity Context Prior knowledge

Goals of our sensory systems Minimizing ambiguity…

Goals of our sensory systems Minimizing ambiguity…

Goals of our sensory systems Minimizing ambiguity…

Goals of our sensory systems Minimizing ambiguity…

Sensory perception Is what you see, what you perceive?

Sensory perception Is what you see, what you perceive? Not necessarily… naïve realism Sensation does not equal perception!

Sensation vs. Perception Sensation – reception of an environmental stimulus Perception – process of interpreting and understanding sensory information

Sensation vs. Perception Visual Illusions A C 3 14

Sensation vs. Perception Auditory Illusion Shepard tones

Sensation vs. Perception What you see and hear is not necessarily what you see and hear! Examining errors provides insight into sensory perception

An example from vision You will have 15 seconds to study the following picture. Then draw what you remember on the provided worksheet.

How do your drawings compare?

Boundary Extension

What does this tell us about the visual system? Context and prior knowledge influences what we remember seeing

Boundary Extension Perceptual Schema Hypothesis: BE caused by mental representation (schema) of the scene’s likely layout Expected information becomes incorporated into your memory for the scene Due to physiology of visual system we are not able to view a scene in its entirety. Helene Intraub

An example from audition Representational momentum Context influences memory for pitch

Representational Momentum Probe Increasing Pitch Sequence Length Time

Representational Momentum Increasing Pitch Time Sequence Length Decreasing Pitch Sequence Length Time

Representational Momentum P(same) Relative Pitch Shift of Probe Tone 0- cents+ cents Ascending Descending

Representational Momentum

What does this tell us about the auditory system? Context influences what we remember hearing

Representational Momentum Pattern-based expectancy hypothesis: listeners form general expectations based on the structure of the sequence biased to expect the pattern to continue Context influences memory for pitch Johnston & Jones

Representational Momentum What will happen with this pattern? Pitch Time Sequence Length 123

Representational Momentum What will happen when loudness changes are present in the pattern?

Representational Momentum Congruent Pitch Sequence Length Time Positive correlation (r = +1) between pitch and loudness changes

Representational Momentum Time Incongruent Pitch Sequence Length Negative correlation (r = -1) between pitch and loudness changes

Representational Momentum Positive correlation between pitch and loudness Still more likely to respond ‘same’ to higher probes Negative correlation between pitch and loudness Now equally likely to respond ‘same’ to higher and lower probes Congruency between pitch and loudness changes influences perception!

Summary Sensation does not always equal perception Goals of sensory system: Allows effective interaction with objects and events in the environment Minimizes ambiguity in the stimulus based on context and/or prior knowledge

Summary Examining errors provides insight into sensory perception Boundary extension Representational Momentum Context and prior knowledge influences what you remember seeing and hearing

Can you think of other instances where your senses might deceive you?

Thank you!