Sensory Adaptation in AP Psychology

Receptors going quiet vs. a brain learning to ignore

The fastest way to get sensory adaptation right is to set it next to habituation, the term it gets confused with most. In sensory adaptation, the change happens at the sense organ. Receptors firing at a steady input send fewer signals, so the information never reaches the brain at full strength. You can't will yourself to smell your own cologne again after it has faded.

Habituation is a learning concept. The receptors still detect the stimulus fine, but you stop responding because it has proven unimportant. You habituate to a ticking clock, and you can hear it again the moment you pay attention.

A quick test for a scenario: ask whether the person could notice the stimulus again just by focusing on it. If yes, lean habituation. If the signal itself has weakened, like the feel of a watch on your wrist or the smell of a room you've been sitting in, it's sensory adaptation.

Why adaptation sits next to the JND and Weber's law in 1.6

Telling 20 candles from 21 and no longer hearing a constant hum both fall under Topic 1.6 Sensation in Unit 1: Biological Bases of Behavior, where the course asks how the process of sensation connects to behavior and mental processes. The essential knowledge groups sensory adaptation with the just-noticeable difference (JND) because both explain how the senses handle change and reduced sensitivity.

They answer different questions, though. The JND is the smallest change in a stimulus a person can detect, and Weber's law says that change has to be a constant proportion of the original intensity. Adaptation is about what happens when nothing changes at all. A stem about whether someone can tell 20 candles from 21 is a JND or Weber's law item.

A stem about someone who stops noticing a constant hum after an hour needs a closer read. A fading hum could illustrate either sensory adaptation or habituation, so look for evidence that sensory sensitivity itself dropped, rather than just attention or response to the sound.

The behavioral payoff is that sensation doesn't record everything equally. Steady input gets turned down, which frees up attention for anything new. That same filter can cause problems, like someone who stops smelling a gas leak after sitting in the room for a while.

Adaptation across the senses, and the stuffy-nose trap

Topic 1.6 covers vision, hearing, the chemical senses, touch, pain, and the body senses, and adaptation scenarios can come from any of them. A refrigerator hum fades (hearing). A strong odor fades (smell). Pressure from clothing fades (touch). The fifth sip of a sweet drink tastes less sweet (taste).

The trap is sensory interaction, which the course defines as the senses working together constantly. A chef with a stuffy nose who says the soup tastes bland is a sensory interaction case, because taste is muted without smell. Nothing about that situation involves a constant stimulus wearing down a receptor's response.

Watch the word "adaptation" in vision too. The course says rods help with light and dark adaptation. Dark adaptation means your eyes become more sensitive after you walk into a dark theater, which runs in the opposite direction from the diminished sensitivity in sensory adaptation. If a question is about seeing better in dim light over time, think rods and dark adaptation.

Reading an odor-fading study in the Article Analysis question

Adaptation research fits naturally into Question 1 (Article Analysis), or into a multiple-choice set built around a study. Take a study where participants rate the intensity of a constant odor. Ratings start at 8.5 out of 10, drop to 6.2 after 10 minutes, and fall to 2.1 by 30 minutes, while the odor concentration stays the same.

Here's how a strong answer breaks that down:

• Variables: the independent variable is time exposed to the odor. The dependent variable is the intensity rating. Odor concentration is held constant, which is what lets the drop count as evidence of adaptation instead of a weakening smell.
• Support for the concept: perceived intensity falls even though the physical stimulus stays constant. That's evidence consistent with sensory adaptation, though ratings alone don't rule out habituation or other changes in how participants respond.
• Statistics: in a related study, 18 participants adapt to forearm pressure in times ranging from 8 to 26 seconds, with a standard deviation of 5.2 seconds. The standard deviation shows that participants' measured adaptation times varied. The mean isn't given, and the range alone can't tell you what it is or how many participants fall within about 5 seconds of it. No calculator is allowed, so be ready to reason about what spread does and doesn't tell you without computing it yourself.
• Generalizability: 18 participants is a small sample, so you'd want a larger, more varied group before claiming the timing applies to people broadly.

On Question 2 (Evidence-Based), adaptation could anchor a claim about why people stop noticing environmental stimuli. Cite a specific finding from a source, then explain in your own words how that finding fits reduced sensitivity to a constant stimulus. Naming the term without linking it to the evidence won't earn the reasoning point.