Roy Lachman

The effects of stimulus uncertainty and S-R transitional probability on paired-associate learning

The Associative Probability Theory asserts that the greater the number of associates elicited by a stimulus, the greater the probability that one of these will be an appropriate mediator for new learning. The present study tested the adequacy of this theory in decribing the effect of natural-language-sequential habits on PA learning. The transitional probability between pairs of words and the uncertainty of the probability distribution of words following a given word were computed from 985 student essays. On the basis of these norms, 3 PA lists were constructed with the stimulus terms either high or low in uncertainty and with either high or low transitional probabilities between stimulus and response terms. In all three lists fewer errors were made in learning pairs of high transitional probability but, contrary to expectations from the extension of Associative Probability Theory, stimuli of high uncertainty resulted in more errors.

Apparatus for Selective Learning Research with Low-Cost Teaching Machine Potential

A fully automatic apparatus is described for investigations of concept formation and a variety of verbal learning problems. The machine will administer a series of experimental learning tasks with automatic changes in stimuli and reinforcement between problems. A relatively inexpensive component of the apparatus functions as a highly versatile teaching machine.