Antagonistic visual discrimination habits in the white rat.

Abstract

This research was an attempt to investigate further the phenomenon reported by Fritz (2) viz., the inability of the white rat to decrease the time of reversed discrimination habits upon repetition. Fritz trained 4 rats to discriminate between two alleys on the basis of a visual stimulus. After the animals had learned to choose the alley with a lighted window as the one leading to food, Fritz reversed the stimuli and the animal had to learn to avoid the lighted window and go towards the darkened one. One animal was given a series of 13 reversals; another, 7; the third, 5; and the fourth, 3. On the basis of his results Fritz concluded that "except for negative transfer, each reversal seems to be more or less of an independent learning period" and that therefore his results "seem to confirm Hunter's'belief that the white rat does not employ symbolic processes."Fritz was cognizant of the fact that the validity of any conclusions to be drawn from his experiment was "partly a function of the length of time the experiment is continued" and he therefore states that "an attempt was made to prolong the experiment until there seemed to be reasonable grounds for assuming that ample opportunity had been given for the display of abilities particularly in the case of one rat." Fritz apparently measured "length of the experiment" by the total number of trials (not reversals) he gave the animals and the total number of days the animate were subjected to training, for he points out in his conclusion that the duration of the training period "in the case of 1 rat lasted for a period of time equivalent to 12 years in the lifetime of man."It appeared to the writer, however, that the validity of the 263

SUCCESSIVE REVERSALS OF A CLASSICALLY CONDITIONED HEART‐RATE DISCRIMINATION1

“…There is a striking resemblance between the error curves generated under the training conditions of the present experiment and the error curves reported for instrumental reversal learning in the rat with both position and brightness discriminations (Dufort, Guttman, and Kimble, 1954;Fritz, 1930;Krechevsky, 1932;North, 1950aNorth, , 1950bPubols, 1957). As in the present experiment, successive reversal learning under instrumental procedures yielded a sharp rise in errors during the early reversals, followed by a progressive and marked improvement in performance.…”

The relationship between transfer and the length of the interval separating the mastery of the two problems.

“…Several experimental studies (4,5,6,7,8,11) have indicated that the locus of the transfer effect in the mastery of the second problem is in the initial stages of the latter task. Apparently, in the case of positive transfer, the learning of the first task enables the learner to start the second problem at a higher level of efficiency than would otherwise occur.…”

Autoshaped Head Poking in the Mouse: A Quantitative Analysis of the Learning Curve

“…However, it has often been pointed out that the group-average learning curve may not describe what is seen in individual subjects (Brown & Heathcote, 2003;Estes, 1956;Krechevsky, 1932;Lashley, 1942;Mazur & Hastie, 1978;Restle, 1965). If the change in the strength of each individual subject's behavior is step-like, but the steps occur after different amounts of experience and have different heights, averaging across them yields a gradually asymptoting function, the parameters of which do not estimate the values of the parameters of any function appropriate to an individual subject.…”