1. Sensation and Perception
Chapter 4

2. Objective Distinguish between sensation and perception
Explain how they contribute to an understanding of our environment

3. Sensation and Perception
Sensation: Stimulation of sensory receptors and the transmission of sensory information to the central nervous system.
Sensory Organs: eyes, ears, nose etc.
Automatic
Perception: Psychological process through which we interpret sensory stimulation.
Reflects learning, expectations, and attitudes

4. Concepts for interpreting stimulation
Stimulation of the senses and the ways in which people interpret that stimulation is affected by several concepts.
Absolute threshold
Difference threshold
Signal-detection theory
Sensory adaptation

5. Absolute Threshold
Absolute Threshold: The weakest amount of a stimulus that can be sensed.
Dogs can hear whistles humans can’t.
Their absolute threshold is different from ours
Absolute thresholds for humans have been determined for the senses of vision, hearing, smell, taste, and touch
Difer from person to person
More sensitive to certain sensory stimuli than others
If absolute thresholds differed much from what they are, we might sense the world differently

6. Absolute Thresholds

7. Difference Threshold
Difference Threshold– minimum amount of difference that can be detected between two stimuli.
For example, let's say I asked you to put your hand out and in it I placed a pile of sand. Then, I add tiny amounts of sand to your hand and ask you to tell me when you notice any change in the overall weight. As soon as you can detect any change in the weight, that difference between the weight of the sand before I added that last bit of sand and the amount of sand after I added it, is the difference threshold.
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8. Signal-Detection Theory
Signal-Detection theory– a method of distinguishing sensory stimuli that takes into account not only their strengths but also such elements as the setting, your physical state, your mood, and your attitude.
Considers psychological factors
Motivation
Expectations
Learning
Ex: Reading a book; can ignore distractions if you are motivated to read.

9. Sensory Adaptation
Sensory Adaptation: the process by which we become more sensitive to weak stimuli and less sensitive to unchanging stimuli
Turn out the lights, can’t see, as your eyes adjust to the dark you are able to see more clearly.
Live in the city, adapt to the noisy surroundings.