Stress and learning

by prescotthbreeden

The Yerkes-Dodson Law

In 1908, Yerkes and Dodson published findings of a remarkable phenomenon they discovered regarding the relationship between arousal and performance.  The law asserts:

  1. The speed of learning and performance increases with arousal; however, it quickly reaches an optimal intensity where learning and performance then deteriorate.
  2. Both weak stimuli and strong stimuli result in slow habit-formation.
  3. The more difficult the task, the lower the optimal level of arousal for maximum performance.
  4. “A stimulus whose strength is nearer to the [minimum] threshold than to the point of harmful stimulation is most favorable to the acquisition of a habit.”  (Yerkes & Dodson, 1908)

Yerkes-Dodson Law

Hebb's graph of the Yerkes-Dodson Law (image source: wikipedia)

Hebb’s graph of the Yerkes-Dodson Law (image source: wikipedia)

Two things eventually arise from dog training methods that involve prolonged arousal or stress.  First, as cognitive function deteriorates, behavior becomes resistant to extinction.  Thus if our objective is to make a particular behavior diminish or stop, in actuality the stress initially preserves the ineffectual behavior (Schwabe & Wolf, 2011).  As stress continues to move in the “high” range of the graph above, corticosteroids are actively being pumped by the hypothalamo-pituitary-adrenal (HPA) axis to support sympathetic nervous system activity (commonly referred to as “fight or flight”).  When these systems are stimulated excessively—because the physical well-being of an animal is at harm—an animal’s learning for a survival strategy impedes learning of the task/behavior (Joels et al., 2006).  Eventually, as learning and performance come to a halt, a dog enters a state of learned helplessness.

Harsh punishment and the “Hang” – a dog’s fight for survival

In a case study published in the Journal of Veterinary Behavior (Grohmann et al., 2013), a German Shepherd was diagnosed with severe cerebral edema resulting in ischemic brain damage from a training session with its owner.  When the dog failed to perform desirably, the owner “disciplined” the dog by hanging it on its leash with an equipped choke chain for 60s.  Brain ischemia, or cerebral ischemia, is caused when there is a lack of oxygen rich blood flow to the brain causing cerebral hypoxia and brain death—in layman’s terms: death or brain damage by strangulation.  Other presenting conditions included:

  • Anxiety
  • Panting
  • Tachycardic (racing heart beat)
  • Severe disorientation
  • Pleurothotonus (abnormal and sustained involuntary muscle contractions)
  • Blindness
  • Bilateral mydriasis
  • Left-sided facial motor paralysis

Medical differentials for the presenting conditions included diffuse axonal injury, vascular ischemia, increase in intracranial pressure, and hemorrhage.  The dog was euthanized after the diagnosis was made and the owner declined a postmortem examination.

All I can think about when I read stories like this is: what was going through the mind of that poor dog, an emotional and sentient being, as the choke chain cut off blood and oxygen to the brain?

What is dog training

Dog training is literally the act of teaching a dog to perform a certain task—whether it is a sit or to stop lunging on leash—a task which ultimately requires the dog to make a successful decision.  This is a complex physiological process that involves 3 things: the cognitive processing of relevant information, the estimation of relationships between actions and their potential consequences, and use of executive functions to optimize decision-making performance (Mair et al., 2011).

Prolonged and severe stress has deleterious effects on cognitive function, memory formation, and performance (McEwen & Sapolsky, 1995; Yerkes & Dodson, 1908)

Owners and trainers need to abandon confrontational methods and techniques, teach dogs ‘English as a Second Language’, talk to them like a loving parent, learn their cognitive landscape by playing and interacting with them, and enjoy the fact that they are not a robot: they are an individual with complex biological emotions and thoughts.

References:

Grohmann, K., Dickomeit, M. J., Schmidt, M. J., & Kramer, M. (2013). Severe brain damage after punitive training technique with a choke chain collar in a German shepherd dog. Journal of Veterinary Behavior: Clinical Applications and Research. doi:10.1016/j.jveb.2013.01.002

Joëls, M., Pu, Z., Wiegert, O., Oitzl, M. S., & Krugers, H. J. (2006). Learning under stress: how does it work? Trends in Cognitive Sciences, 10(4), 152–158. doi:10.1016/j.tics.2006.02.002

Mair, R. G., Onos, K. D., & Hembrook, J. R. (2011). Cognitive Activation by Central Thalamic Stimulation: The Yerkes-Dodson Law Revisited. Dose-Response, 9(3), 313–331. doi:10.2203/dose-response.10-017.Mair

McEwen, B. S., & Sapolsky, R. M. (1995). Stress and cognitive function. Current opinion in neurobiology, 5(2), 205–216.

Schwabe, L., & Wolf, O. T. (2011). Stress increases behavioral resistance to extinction. Psychoneuroendocrinology, 36(9), 1287–1293. doi:10.1016/j.psyneuen.2011.02.002

Yerkes, R., & Dodson, J. (1908). The relation of strength of stimulus to rapidity of habit-formation. Journal of Comparative Neurology and Psychology, 18, 459–482.