Sensation vs. Perception

Sensation = detection of a stimulus + conversion into a neural signal (transduction). Perception = organizing/interpreting/consciously experiencing that signal.
Optical illusions: sensation (raw input) stays identical, only perception (interpretation) changes — classic sign a question is testing perception.
6 receptor types: photoreceptors (light), mechanoreceptors (touch/pressure/vibration/sound/balance), thermoreceptors (temperature), nociceptors (tissue damage/pain), chemoreceptors (smell/taste), osmoreceptors (fluid concentration/thirst).
Absolute threshold = minimum stimulus intensity a sensory system can detect at all. Threshold of conscious perception = the higher bar for a detected stimulus to reach conscious awareness — detection ≠ awareness.
Difference threshold (JND) = smallest detectable change in a stimulus; Weber's law = that change is PROPORTIONAL to the original stimulus intensity, not fixed.
Signal detection theory: 4 outcomes — hit (signal present, detected), miss (signal present, missed), false alarm (no signal, reported present), correct rejection (no signal, correctly reported absent).

Transduction: Sensory receptors converting light, sound, temperature, pressure, or chemical stimuli into neural electrical signals.
Absolute threshold: Minimum stimulus intensity a sensory system can detect at all.
Threshold of conscious perception: The level at which a detected stimulus becomes strong enough to enter conscious awareness.
Difference threshold (JND): The just noticeable difference — smallest change in a stimulus a person can reliably detect.
Weber's law: The JND is proportional to the original stimulus intensity, not a fixed amount.
Signal detection theory: Studies how attention, expectation, and noise shape detection of a stimulus under uncertainty.

Signal Present?	Response → Outcome
Yes	Detected → Hit (correct)
Yes	Missed → Miss (incorrect)
No	Reported present → False alarm (incorrect)
No	Reported absent → Correct rejection (correct)

A passage describing identical sensory input producing two different conscious experiences (classic illusion) is testing perception, not sensation.
Detecting a stimulus (absolute threshold) is NOT the same as consciously noticing it (threshold of conscious perception) — a stimulus can clear the first without clearing the second.
Weber's law is about proportion, not a fixed amount — the same absolute change is noticeable at low intensities but not at high intensities.
Miss and false alarm are both errors but in opposite directions — a miss is a real signal going undetected, a false alarm is reporting something that wasn't there.

Which receptor type detects tissue damage and produces pain?

What is the difference between absolute threshold and threshold of conscious perception?

According to Weber's law, does the same absolute increase in stimulus intensity feel equally noticeable at low and high starting intensities?

In signal detection theory, what outcome occurs when a real signal is present but goes undetected?

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