“Cues for Spontaneous Alternation”, 1966 (; backlinks):
Large numbers of possible cues for spontaneous alternation by rats in T mazes were tested both in isolation and in combination in an attempt to discover which stimuli determine the response.
Free-trial spontaneous alternation represents the addition of a relatively weak odor-trail avoidance and a much more powerful tendency to turn in opposite directions at a choice point. No other effective alternation cues could be found, and the magnitude of these 2 tendencies was sufficiently high to account for all observed alternation.
It is suggested that rats, at least, have a sense of relative direction or position in space, and that the receptors are located in the inner ear.
…Experiment 3: Experiment 1 showed that alternation of extramaze cues occurred at a high (75%) rate. In the following experiment an attempt was made to discover the specific types of stimuli which might have contributed to this alternation. The effectiveness of visual and auditory cues, odor differences, and deep-floor stimuli were tested both individually and in combination.
…Deep-floor cues: The possibility of deep-floor cues being important in alternation wag suggested by the work of 1959, in which these cues were suspected of being important in the learning of complex mazes by the rat. The effectiveness of floor resonance differences as alternation cues was tested through the use of a special subfloor, constructed for this purpose, which was large enough (23×42 in.) to form a floor for the entire maze. The right half of this floor was made of 3 layers of 1⁄4-in fiberboard, while the left half was a solid piece of 3⁄4-in. plywood. The dividing line between the two halves was placed under the centerline of the main alley so that the right half of the main alley and the entire right side alley were over the fiberboard layers. The subfloor was placed on the previously used tables, and raised from the surface by 3⁄4-in. wood pedestals. A finger tap on either side produced noticeably different sounds.
[Although it’s unclear how floor cues would cause randomized alternation, anyway…]
The subjects were tested by giving them 1 trial in each maze and room, with the subfloor used on both trials, but covered with a new paper floor for each trial in order to rule out odor-trail cues. The intertrial interval was 40 sec., and two sessions were run, for a total of 96 observations.
Odor differences: Even though the possible odor differences within a maze had been dismissed as alternation cues, it was still not known whether strong odor differences might produce alternation. This possibility was tested through the use of different smelling substances which were actually placed within the maze, although it was suspected that if odor differences were normally used by rats they might well originate outside the maze. The olfactory stimuli were a liquid soap with a strong peppermint smell and a decidedly aromatic pipe tobacco, placed in open vials and taped to the insides of the ends of the cross alleys. Tobacco was at the left in both mazes and the soap at the right; positions were not switched because of a fear that the effects might be lingering. The subjects were given 1 trial in each maze and room, with an intertrial interval of 10 sec. or less. Each subject was run on two different occasions for a total of 96 observations.
…Results: …Deep-floor or vibratory cues: Alternation to subfloor cues was found at a rate of 52.1%, with no stimulus bias present. This did not, of course, come close to being statistically-significantly different from chance, and it can be concluded that deep-floor cues probably did not affect alternation, as these cues were far more intense than would be found in the usual subfloor underlying a maze.
…The evidence now appears to clearly favor the hypothesis that alternation is based on a relatively weak odor-trail avoidance tendency interacting additively with a much more powerful tendency to turn in opposite spatial directions at a choice point. Evidence for the first factor consists of the findings that rats alternated at a moderate rate when the only constant cues available on the two trials were those provided by the paper floor. In Experiment 2 it was shown that this tendency is probably not due to the possible visual or tactile cues associated with this floor.
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