In a Study of the Conditions Affecting Conditioning, Four Groups

In a study of the conditions affecting conditioning, four groups of dogs were presented a tone and food powder. The tone, which lasted for four seconds, began eight seconds before the food powder, two seconds before, at the same time the food powder was presented, or two seconds after the food powder was presented. (You might draw a graph of these four conditions as a way of being sure you understand.) The dependent measure was the number of drops of saliva elicited by the tone alone after 50 pairings of the tone and food powder. Group means, an ANOVA summary table and the results of some HSD tests are shown below. Write an interpretation of the results. $\begin{array}{lc}\text { Conditions } & \text { Mean Drops of Saliva } \\\hline 8 \text { seconds before } & 27 \\2 \text { seconds before } & 54 \\\text { simultaneous } & 14 \\2 \text { seconds afterward } & 3\end{array}$

$\begin{array}{lrrr}\quad \text { Source } & d f & M S & F \\\hline\text { Conditions } & 3 & 362.25 & 7.96 \\\text { Error } & 20 & 45.51 &\end{array}$

$\begin{array}{cc}8 \text { vs. } 2 \text { seconds before } & 2 \text { seconds before vs. simultaneous } \\H S D=3.78 & H S D=3.60\\&\text { Simultaneous vs. 2 seconds afterward}\\&H S D=1.85\end{array}$