Sensation and Perception

Stimulus - Any aspect of or change in the environment to which an organism responds.

Sensation - what occurs when a stimulus activates a receptor

Perception - The organization of sensory info into meaningful experiences.

Psychophysics - the study of the relationships between sensory experiences and the physical stimuli that cause them.

Absolute Threshold

• the weakest amount of a stimulus that a person can detect half the time.
• (hearing tests at school

Absolute Thresholds

• vision - candle 30 miles away
• hearing - watch ticking 20 ft away
• taste - 1 teaspoon of sugar in 2 gallons of water
• smell - 1 drop of perfume in a 3 room house
• touch - a bee's wing falling a distance of 1 centimeter onto your cheek

Difference Threshold - the smallest change in a physical stimulus that can be detected half the time

Weber's Law

• The larger or stronger the stimulus, the larger the change required for a person to notice that anything has happened to it.

Sensory Adaptation

• Senses are tuned to change
• We can respond to changes in our environment with our ability to adapt

Signal-detection theory - the study of people's tendencies to make correct judgements in detecting the presence of stimuli

Signal-Detection Theory

• Preattentive - method of extracting info automatically and simultaneously
• Attentive - considering only a part of the stimuli presented at a time