“The Effects of Olfactory Cues on the Maze Learning of White Rats”, 1940 (; backlinks):
A number of investigators have studied the role of olfaction in the maze learning of white rats, but few have studied the use of this sensory cue under conditions which might actually be encountered in a maze learning experiment…This poor vision of the rat and the continual sniffing and smelling that characterizes the rat’s responses to its surroundings indicates that the olfactory sense might play a more important part in maze learning than is generally conceded.
Since most mazes are not equipped with movable floors there is a possibility that definite rat odor trails might be formed which would influence the time and error scores of rats learning the maze. This study was designed to investigate just such a possibility.
…Throughout Experiment 1, an elevated multiple-T maze was used.
…Conclusions [for Experiment 1]:
Rats running a maze in which there is a true olfactory trail are more homogeneous when time scores are considered and more heterogeneous when error scores are considered than rats running a maze in which no olfactory cues are present or in which the blind alleys are marked. This indicates that rats running a maze in which there is a true olfactory trail do not tarry as long in the blind alleys as do rats running the maze in which no olfactory cues are present or in which the blind alleys are marked.
Reliable differences may be produced in time and error scores by the presence of definite animal odor trails in the maze.
The presence of definite animal odor trails in the maze tends to aggravate individual differences especially when error scores are considered.
In the maze learning of some rats the olfactory sense is undoubtedly of major importance when definite animal odor trails are present.
…Experiment 2: The purpose of this experiment was to determine the olfactory distractibility of rats, that had learned the maze, by the introduction of strange or new olfactory cues.
…Conclusions:
The data from Experiment 2 indicate that the introduction into the blind alleys of the maze of old male and female odors in no way disrupts the maze running of rats if these rats have previously learned the maze with definite animal odor trails present.
The possibility that an odor trail in the true path of the maze might have caused some disturbance in the maze running must be referred to some future research since only the blind alleys were marked in this experiment.
…Olfactory cues that may be formed in the alleys are impossible to control in many mazes, or no controls have been attempted because some investigators thought that olfactory cues were of little or no importance. Evidence was found in the present investigation that the presence of definite animal odor trails in the maze produced differences in time and error scores which in one case were completely reliable and in other instances approached reliability. If the animal odor trail was in the blind alleys many rats were led into making more errors and taking a longer time in running the maze than did those running the maze with no odor trail present or an odor trail in the true path. The rats running with a true olfactory trail present made lower total time and error scores than were made by the other rats. This group also exhibited the greatest heterogeneity of any of the groups in regard to the number of errors made. In any experiment, then, in which olfactory cues are not controlled the variability of the group may be increased and this increase in variability will be accompanied by a spurious rise in the reliability coefficients.