Epigenetics: What do Psychologists Need to Know?

This paper reviews the rapidly developing field of epigenetics, providing an accessible explanation of the key ideas and some illustrative examples of work in the field. Although very much a biological discipline the implications of the developing knowledge in this area are very significant for educational psychologists and this paper aims to provide an introduction to what is becoming a very significant shift in how people think about learning and development. Understanding the processes that underlie epigenetic change and the research that the new knowledge is based on will be important for educational psychologists in order to understand this important developing area of thinking about development and learning. Consensus is growing that intergenerational transmission of epigenetic changes are a reliable phenomenon, establishing the principle of the inheritance of acquired characteristics. This contrasts starkly with models of biological determinism and provides a new way of thinking about educational and societal change.

Humphreys' “Acquisition and Extinction of Verbal Expectations” Revisited: Evidence for a Partial Reinforcement Hump Effect

The present study employed the sequential prediction task to determine whether the partial reinforcement hump effect—a rise in the dependent variable curve following partial reinforcement—is a reliable phenomenon. 210 college students received one of seven sequences in which two events occurred equally often for 100 trials and in which the maximum run length was 2, 3, 4, 5, 6, 7, or 8, followed by 30 trials during which one event was always correct. A hump appeared in the post-acquisition curves of all seven groups. The location of the hump was a function of the maximum run length during Trials 1–100. These results provide strong support for an expectancy interpretation of the partial reinforcement extinction effect.

Interruption of Escape Training and its Effect on Lever-Holding

It has been reported, previously, that as escape-from-shock training progressed, Ss increasingly held the lever down. This was true both when shock termination was contingent upon a lever press (press training) and when it was contingent upon release following a press (release training). Moreover, changes in holding were not primarily reflected by changes in response duration but, rather, by shifts in the relative frequencies of responses which were held until the reintroduction of shock, particularly, in press training, escapes which were held until the reintroduction of shock (punished escapes) and, in release training, extra responses which were held until shock returned (punished extras). Finally, the writer had observed some indications that interruption of release training temporarily reduced holding. The present study was undertaken to determine whether the decremental effect of rest on holding is a reliable phenomenon and whether it is obtained with press as well as with release training. Ss were trained at one of four degrees of inter-session time (0, 1, 5, or 10 days of rest) and under either the press or release training procedure. In press training the over-all effect of inter-session time on holding (change in relative frequency of punished escapes) was not significant. The pattern of effects was comparable to those attributed to fatigue or other inhibitory factors which dissipate rapidly during rest. In release training, the effect of inter-session time on holding (change in relative frequency of punished extras) was predominantly decremental. That is, in release training, rest reduced holding. These results are comparable to those commonly attributed to the establishment of competing or interfering stimulus-response relations during rest. A theoretical analysis of response chaining accounted for the interaction of training procedure and inter-session time and indicated, as did supporting data, that delays in training reduced the strength of extra presses, i.e., their initiation, and did not reduce holding per se.