A researcher conditions rats to fear a tone that was sounded just prior to a brief shock.To measure fear following this conditioning,she records the number of lever presses by each rat in the presence and in the absence of the tone.It was hypothesized that reduced lever pressing in the presence of the tone was evidence for a conditioned fear response in rats.If the researcher tested this hypothesis at a .05 level of significance (two-tailed test),then what is her decision if she computes t = -2.842 in a sample of eight rats.
A) Retain the null hypothesis; there is evidence for a conditioned fear response.
B) Retain the null hypothesis; there is no evidence for a conditioned fear response.
C) Reject the null hypothesis; there is evidence for a conditioned fear response.
D) Reject the null hypothesis; there is no evidence for a conditioned fear response.

Question

Quizplus · Accepted Answer

The researcher conducted a two-tailed test at a significance level of .05, which means that the critical t-value is +/-2.306 (with df = 7). Since the computed t-value (-2.842) is more extreme (farther from zero) than the critical value (-2.306), we can reject the null hypothesis and conclude that there is evidence for a significant difference in lever pressing between the presence and absence of the tone. Therefore, the conditioned fear response hypothesis is supported.

A Researcher Conditions Rats to Fear a Tone That Was