Krech, Rosensweig and Others at the University of California, Berkeley

Krech, Rosensweig and others at the University of California, Berkeley, thought that brain chemistry could account for intelligence. In particular they thought that acetylcholine (ACh), a neurotransmitter, was responsible. Fortunately for them, Tryon had bred strains of maze-bright and maze-dull rats in the 1930's and these strains had been maintained there at Berkeley. Sure enough, the maze-bright animals had high ACh levels (as measured indirectly). Next the researchers selectively bred rats for high ACh levels. The scores below are errors in learning a complicated maze. Analyze them and write a sentence of explanation of what the results show (which will be what Krech, et al. found). $$\begin{array} { c c } \begin{array} { c } \text { Bred for high } \\\text { levels }\end{array} & \begin{array} { c } \text { Bred for low } &\text { ACh} \\\text { ACh levels }\end{array} \\\hline 25 & 25 \\26 & 26 \\29 & 21 \\27 & 24 \\29 & 22 \\28 & 23\end{array}$$