The Dancing Mouse: A Study In Animal Behavior Informative Summary

Overview:

This book is a detailed and insightful exploration of the dancing mouse, a variety of mouse known for its peculiar whirling movements. Author Robert Mearns Yerkes, a comparative psychologist, was first drawn to the dancing mouse when he received a pair at the Harvard Psychological Laboratory. This led him to conduct a series of experiments, meticulously observing the mice’s behavior and seeking to understand the underlying neurological and anatomical factors contributing to their unique traits.

The book delves into various aspects of the dancing mouse’s life, including its feeding, breeding, and the development of its young. Yerkes debunks the common myth that dancing mice are fragile and delicate, highlighting the importance of proper care and diet. He also conducts detailed investigations into the dancing mouse’s senses, particularly its hearing and sight. While proving the adult dancing mouse to be totally deaf, he discovers that young mice exhibit a short period of hearing during their third week of life.

Key Findings:

  • Dancing mouse is not delicate: Contrary to common belief, dancing mice are not exceptionally fragile and can be successfully bred and raised with proper care.
  • Dancing mouse is totally deaf: Yerkes’s extensive experiments with adult dancing mice reveal a complete lack of auditory response, leading him to conclude that they are totally deaf.
  • Young mice have a brief auditory period: Surprisingly, young dancing mice exhibit a short period of hearing during their third week of life, coinciding with a noticeable increase in excitability.
  • Dancing mouse has brightness vision: Yerkes proves that dancing mice can discriminate between different levels of brightness, demonstrating the presence of brightness vision.
  • Dancing mouse does not have color vision: Extensive and varied experiments demonstrate that dancing mice do not have the same color vision as humans, struggling to differentiate colors like green from blue or violet from red, and possibly having a different perception of brightness values.

Learning:

  • The importance of proper care for animals: Yerkes’s success in raising and breeding dancing mice highlights the crucial role of providing a clean, warm, and nutritious environment.
  • Understanding animal behavior through observation: The book emphasizes the importance of meticulous observation and experimentation in uncovering the nuances of animal behavior.
  • Challenges in interpreting animal behavior: Yerkes’s work showcases the difficulties in interpreting animal behavior, highlighting the need for careful design of experiments to eliminate potential confounding factors.
  • The limitations of human perspective: Yerkes’s findings concerning the dancing mouse’s senses underscore the importance of recognizing that animals might perceive the world differently from humans.
  • The complexities of sensory perception: The book reveals the multifaceted nature of sensory perception, demonstrating that senses like hearing and sight can be highly specialized and exhibit unexpected variations across species.
  • The dynamic nature of behavior: Yerkes’s observations of the dancing mouse’s changing behavior over time and its response to learning experiences demonstrate the dynamic and malleable nature of animal behavior.

Historical Context:

This study was written in 1907, a time when the understanding of animal behavior was still developing. There was considerable debate regarding the nature of animal intelligence, and the concept of “instinct” was still widely accepted. While Yerkes’s work doesn’t directly engage in these debates, it provides a foundation for understanding the complexity of animal behavior and the need for careful scientific inquiry to unravel its mysteries.

Facts:

  1. Dancing mice originated in China and were introduced to Japan. This is supported by the common names “Chinese dancing mouse” and “Japanese dancing mouse.”
  2. Dancing mice are typically smaller than common mice. This is a consistent observation among multiple researchers.
  3. Dancing mice exhibit a distinctive “dance” characterized by whirling, circling, and figure-eight movements. This defining behavior is the basis for their name.
  4. Dancing mice are more active in the evening. Their activity levels increase from morning to evening, suggesting a natural periodicity driven by internal factors rather than external light cues.
  5. Dancing mice exhibit a tendency to turn in a specific direction. Some individuals consistently turn to the right (clockwise), others to the left (anticlockwise), and others exhibit a mix of both.
  6. Dancing mice possess excellent equilibrational ability. They can climb, cross narrow bridges, and balance at heights, despite their whirling tendency.
  7. Dancing mice lack visual dizziness. They do not exhibit symptoms of dizziness when rotated in a cyclostat, unlike common mice.
  8. Dancing mice show limited strength compared to common mice. They can hold up only about 2.8 times their own weight, whereas common mice can hold up 4.4 times their weight.
  9. Dancing mice exhibit a high degree of variability in behavior. Individual differences in activity levels, turning preferences, and even the presence or absence of certain behaviors contribute to their intriguing characteristics.
  10. Dancing mice exhibit individual differences in ear structure. This is confirmed by conflicting anatomical findings, suggesting the potential existence of distinct variations within the species.
  11. Dancing mice lack a typical mammalian cochlea structure. This could potentially explain their deafness, although the precise cause remains inconclusive.
  12. Dancing mice may lack a normal stria vasculosa. This structural peculiarity, which Kishi was the first to identify, might contribute to their deafness, but further investigation is needed.
  13. Dancing mice exhibit a brief period of hearing in their third week of life. This suggests a transient development of the auditory system, followed by complete deafness.
  14. Dancing mice exhibit a sudden increase in excitability during their third week of life. This coincides with the opening of the auditory canal and the brief period of hearing, suggesting a connection between these events.
  15. Dancing mice exhibit a strong tendency to choose a box based on its position. This demonstrates the power of habit formation and the importance of controlling this factor in experiments.
  16. Dancing mice exhibit a preference for darker environments. This is possibly linked to their natural habitat preferences and influences their brightness discrimination.
  17. Dancing mice demonstrate the importance of “punishment” as a motivator in experiments. Yerkes argues that punishment, while requiring careful control, can be more effective than reward in eliciting desired responses.
  18. Dancing mice exhibit three distinct methods of choosing between boxes: affirmation, negation, and comparison. This reveals the complexity of their decision-making process and their ability to learn and adapt.
  19. Dancing mice display a marked preference for the lower end of the visible spectrum. They seem to perceive red as darker than humans do, suggesting a distinct sensitivity to different wavelengths of light.
  20. Dancing mice lack a cone structure in their retinas. This lack of cone cells, typically associated with color vision, aligns with Yerkes’s findings that they struggle to discriminate colors.

Statistics:

  1. An average of 5.4 young mice are born per litter. This figure is derived from Yerkes’s observations of 25 litters, with an equal number of males and females.
  2. The average body length of an adult dancing mouse is 7 to 7.5 cm. This is significantly smaller than the common mouse.
  3. The average strength of a dancing mouse is only 2.8 times its own weight. This compares to a common white mouse’s strength of 4.4 times its own weight.
  4. Dancing mice exhibit a significant increase in activity from 9 AM to 8 PM. This observation suggests a daily periodicity in their behavior.
  5. Females dance more than males. This is observed across multiple time points and suggests potential sex-based differences in their behavior.
  6. Females are more likely to squeak than males. This difference in vocalization suggests potential sex-based differences in vocalization.
  7. Male dancing mice exhibit a slight tendency to turn left more than right. This is in contrast to females, who turn right more often, potentially suggesting an inherited trait.
  8. Nendel’s gray paper No. 10 differs from No. 20 in brightness by an amount near the threshold of discrimination for dancing mice. This indicates a relatively limited ability to differentiate shades of gray.
  9. Dancing mice can discriminate between two lights differing in brightness by .19 or less when the standard light is 80 Hefners. This shows that their discrimination threshold for high-intensity light is relatively high.
  10. Dancing mice can discriminate between two lights differing in brightness by .10 or less when the standard light is 5 Hefners. This demonstrates a lower discrimination threshold for lower-intensity light.
  11. Dancing mice exhibit a 20% error rate when discriminating between a 20 Hefner light and a 9.4 Hefner light. This indicates that their ability to discriminate between similar brightnesses is limited.
  12. Dancing mice exhibit a 41% error rate when the two lights are indiscriminable, both at 80 Hefners. This shows that their choices can be influenced by factors other than brightness alone.
  13. In a preference test series, male dancing mice chose the black box over the white box an average of 4.1 to 5.9 times. This indicates a preference for darker environments.
  14. In a preference test series, female dancing mice chose the black box over the white box an average of 3.8 to 6.2 times. This reflects a stronger preference for darker environments compared to males.
  15. Dancing mice required approximately 200 tests to learn to choose a light gray box over a dark gray box. This demonstrates that their learning process can be slow.
  16. Dancing mice consistently chose the light blue box over the orange or red box in color discrimination tests. This suggests that they might perceive light blue as brighter than the other colors.
  17. Dancing mice exhibited a 9% error rate when discriminating between blue and orange, with blue significantly brighter than orange. This indicates a lack of color discrimination when brightness differences are significant.
  18. Dancing mice showed a 25% error rate when discriminating between green and blue, with colors appearing equal in brightness to the human eye. This suggests a lack of color discrimination when colors are perceived as equal in brightness by humans.
  19. Dancing mice were unable to discriminate between green and blue when both lights were at 18 candle meters. This again suggests a lack of color discrimination, even when brightness is the same for both colors.
  20. Dancing mice showed an 8% error rate when discriminating between green and red, with the red light significantly brighter than the green. This suggests a limited ability to differentiate colors, even when brightness differences are significant.

Terms:

  • Cyclostat: A device for rotating an animal about its vertical axis, used to study dizziness and equilibrium.
  • Hefner: A unit of luminous intensity, equivalent to the light produced by an amyl acetate lamp at a specific flame height.
  • Induction apparatus: A device that generates an electric current, used in the book to provide a mild electric shock as a motivator.
  • Just perceivable difference: The smallest perceptible difference between two stimuli.
  • Mendel’s theory of heredity: A theory of inheritance based on the idea that traits are passed down in discrete units called genes.
  • Otoliths: Small calcium carbonate crystals found in the ear sacs of vertebrates, believed to be involved in equilibrium.
  • Photometer: A device for measuring the intensity of light.
  • Stria vasculosa: A vascular structure in the cochlea, potentially involved in the production of endolymph, a fluid in the ear.
  • Weber’s law: A law stating that the just perceivable difference between two stimuli is proportional to the intensity of the standard stimulus.

Examples:

  1. Saint Loup’s observation of dancing individuals among common mice: This observation supports the theory that the dancing trait may have originated as a mutation in common mice, subsequently amplified through selective breeding.
  2. Cyon’s two types of dancing mice: One group climbed easily and showed auditory responses, while the other did not, suggesting possible variations within the species.
  3. Zoth’s observation of a dancer performing 79 whirls without interruption: This demonstrates the exceptional strength and stamina of dancing mice, challenging the notion of their fragility.
  4. The use of food-box apparatus and electric shock as motivators in color discrimination tests: These methods illustrate Yerkes’s efforts to find more effective and humane ways to motivate the mice in experiments.
  5. The use of different colored cardboards in the discrimination box: This demonstrates the systematic approach Yerkes employed to ensure that the mice were discriminating based on color, not other factors like position or odor.
  6. The use of light filters and transmitted light in color discrimination tests: This highlights Yerkes’s creativity in adapting his methods to control the specific wavelengths of light used as stimuli.
  7. The brightness check tests using different colors and varying brightness values: These tests illustrate Yerkes’s rigorous approach to eliminating confounding variables and ensuring that the mice were responding to color, not brightness.
  8. The observation of three distinct methods of choice (affirmation, negation, and comparison): This highlights the complexity of the dancing mouse’s decision-making processes and their ability to learn and adapt.
  9. The comparison of the dancing mouse’s behavior to that of common mice in response to rotation in a cyclostat: This comparison underscores the unique characteristics of the dancing mouse, which lack the symptoms of dizziness that common mice exhibit.
  10. The observation of a dancer dragging its toes while walking, producing unique tracks compared to common mice: This provides evidence of the dancing mouse’s reduced grasping power.

Conclusion:

This groundbreaking 1907 study reveals that dancing mice are far more complex and fascinating than initially perceived. The book dispels the myth of their frailty, illuminates their unique sensory capabilities and limitations, and offers valuable insights into their learning abilities and behavioral patterns. Yerkes’s meticulous research establishes that the dancing mouse is not merely a “freak” but a distinct species with a fascinating history, a complex neurology, and an intriguing sensory world. Despite limitations in knowledge regarding the underlying neurological structures, the book provides a foundation for future research into the dancing mouse, a remarkable animal that continues to fascinate and challenge our understanding of animal behavior.

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