Study guides › P/S › Psychology
Sensation
Sensation is how the nervous system detects the world and converts it into neural signals. You will learn thresholds and signal detection, then follow light, sound, touch, taste, smell, and balance from receptor to cortex, with the theories the MCAT tests.
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What this chapter covers
- Thresholds, Weber's Law & Signal Detection. Threshold and signal detection vocabulary shows up in research passages, and Weber's law is one of the few psychology calculations.
- The Eye & Photoreceptors. Know the path of light, the rod and cone contrasts, and the odd fact that light hyperpolarizes photoreceptors.
- Visual Processing & Color Theories. Visual-field loss questions and the trichromatic versus opponent-process contrast are two of the most repeated sensation topics.
- Hearing & the Vestibular System. Trace sound from air to cortex, contrast place and frequency theories, and separate conduction from sensorineural deafness.
- Somatosensation, Taste & Smell. Touch receptors, pain theories, and the unique olfactory pathway are frequent discrete questions.
Key points to know
- Absolute threshold = detected 50% of the time; JND = smallest noticed difference
- Weber's law: JND is a constant fraction of the baseline (ΔI/I = k)
- Path of light: cornea → pupil → lens → retina
- Signal flow: photoreceptor → bipolar → ganglion → optic nerve
- Nasal fibers cross at the optic chiasm; each hemisphere sees the opposite field
- Pathway: retina → optic nerve → chiasm → LGN → V1 (occipital)
- Frequency = pitch; amplitude = loudness; timbre = quality
- Ossicles: malleus, incus, stapes; stapes touches the oval window
Try a practice question
Which statement best defines the absolute threshold?
- The smallest difference between two stimuli that can be noticed
- The minimum stimulus intensity detected 50% of the time
- The intensity at which a stimulus is always detected
- The intensity at which receptors stop adapting
Show the answer
B. The absolute threshold is the weakest stimulus detected half the time. The smallest noticeable difference is the difference threshold (JND). Detection 100% of the time describes an easily detected stimulus, not the threshold.
Common questions
What does this chapter cover?
Sensation covers Thresholds, Weber's Law & Signal Detection, The Eye & Photoreceptors, Visual Processing & Color Theories, Hearing & the Vestibular System, Somatosensation, Taste & Smell.
What should I know first?
Absolute threshold = detected 50% of the time; JND = smallest noticed difference Weber's law: JND is a constant fraction of the baseline (ΔI/I = k) Path of light: cornea → pupil → lens → retina
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