Loading your exam home
AP Psychology · Lesson 8 of 10 · Unit 1
You’re reading a preview of this lesson. Already on Pro? Sign in to read it all.
Sensation is the raw data entry system of the nervous system, bridging external physical energy and internal mental life. On the AP Psychology exam, you will apply threshold concepts and Weber’s law to everyday scenarios and interpret psychophysical data in both multiple-choice questions and free-response study summaries.
Preview
You’ve read the first part of this lesson. The rest is part of Pro: about 4 more minutes of reading, plus the quick check.
Sensation is the bottom-up biological process by which our sensory receptors and nervous system detect physical energy from the environment. Perception is the top-down cognitive process of organizing and interpreting that sensory information to give it meaning.
For the brain to use environmental energy (light waves, sound waves, chemical molecules), sensory receptors must perform transduction: converting physical stimuli into neurochemical messages (action potentials) that the brain can read.
Not all environmental energy triggers transduction; a stimulus must reach a specific minimum intensity.
| Concept | Definition | Key Exam Detail |
|---|---|---|
| Absolute threshold | The minimum stimulation needed to detect a particular stimulus at least of the time. | Below this level, stimuli are subliminal (detected less than of the time). |
| Difference threshold (Just-Noticeable Difference / JND) | The minimum difference between two stimuli required for detection of the time. | Scales with the magnitude of the original stimulus. |
| Weber’s law | The principle that to be perceived as different, two stimuli must differ by a constant minimum percentage (not a constant amount). | Expressed as , where is the JND, is the initial stimulus intensity, and is a constant ratio. |
Already on Pro? Sign in