Chapter 5 Introduction to Sensation Sensation: your window to the world Perception: interpreting what comes in your window.

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 processing v. Top-down Processing Our sensory and perceptual processes work together to help us sort out complex processes

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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.

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 Slide studies showed some emotional reactivity (called priming a response). The effects are subtle and fleeting.

Difference Threshold The minimum difference that a person can detect between two stimuli. Also known as Just Noticeable 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.

Because our sensory neurons fire less frequently Sensory Adaptation Diminished sensitivity as a result of constant stimulation. Because our sensory neurons fire less frequently

Conversion of one form of energy to another. Transduction Conversion of one form of energy to another. How is this important when studying sensation? Stimulus energies to neural impulses. For example: Light energy to vision. Chemical energy to smell and taste. Sound waves to sound.