Geoffrey Keppel University of California, Berkeley
The concepts of neural perseveration and consolidation were used to explain learning and memory phenomena by theorists writing in the shadow of Ebbinghaus. Just a few years after Ebbinghaus published his classical monograph, Müller and Pilzecker ( 1900) introduced the notion of perseveration to account for a number of their experimental findings. More specifically, they found that the memory for a set of learning materials was reduced by interpolating a second set of learning materials--the phenomenon of retroactive inhibition. They saw that this loss was unaffected by the similarity of the two sets and that it was greater when the second set was presented immediately after the first set (17 sec) than after a delay of 6 min. To account for these findings, they speculated that neural activity representing the effects of learning continues, or perseverates, following the cessation of practice and continues until the neural trace is fully formed, or is consolidated. They further proposed that any activity that disrupts this consolidation process will adversely affect subsequent recall of the material and that the negative effect of this interpolated activity decreases as the interval between the two tasks lengthens.
In his review of the literature on perseverative neural processes and consolidation of the memory trace, Glickman ( 1961) reported that these ideas were widely held and debated by numerous psychologists during the early 1900s. To impart some of the flavor of these theoretical speculations, I will quote from one of the champions of this point of view: ( DeCamp, 1915):
From the neurological standpoint, in the learning of a series of syllables, we may assume that a certain group of synapses, nerve cells, nerve paths, centres, etc. , are involved. Immediately after the learning process the after-discharge continues for a