In One Experiment, Rats Were Exposed to Combinations of a Tone

question 83

Multiple Choice

In one experiment, rats were exposed to combinations of a tone and a shock. For one group of rats, shocks arrived 50% of the time without any warning; the tone therefore really provided no information. For another group of rats, shocks also arrived occasionally with no warning. But the likelihood of a shock was smaller (below 20%) when there was no tone than when there was a tone. What was the finding?

• A) The second group of rats became fearful whenever a tone was sounded.
• B) Both groups of rats feared the sound of the tone the same.
• C) Both groups of rats came to fear any sound of any kind.
• D) The first group of rats became fearful whenever a tone was sounded.

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Definitions:

Binomial Distribution

A probability distribution that summarizes the likelihood that a value will take one of two independent states under a given number of observations.

Uniform Distribution

A type of probability distribution where all outcomes are equally likely; in a continuous uniform distribution, any value within a specified range is equally likely to occur.

Standard Normal Variable

A random variable that has a normal distribution with a mean of zero and a standard deviation of one.

Random Variable

A variable whose possible values are numerical outcomes of a random phenomenon.