Baby Paul's mother strokes his hair just before he eats. Now when Paul's mother strokes his hair, Paul begins to suck. The stroking is the , and the taste of milk is the .

neutral stimulus; unconditioned stimulus

Explanation:

Neutral stimulus and unconditioned stimulus are two different parts involved in the classical conditioning theory that was developed by Ivan Pavlov who was considered as one of the greatest psychologists and behaviorists of his times while conducting his experiment on dogs.

A neutral stimulus is described as a stimulus that doesn't produce any particular response except focusing on attention. Once the neutral stimulus gets connected with an unconditioned stimulus gives rise to a conditioned stimulus.

An unconditioned stimulus is described as a stimulus that is responsible for triggering a particular response automatically, unconditionally, and naturally.

hygrometers and hair thermometers (often found as part of hygrometers/psychrometers) can be used to measure humidity. barometers are used to measure atmospheric pressure, while anemometers are used to measure wind speed. so the 2nd and 4th choices should be the correct answers.

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