Mechanism of Formation and Characteristics
A dynamic stereotype represents a complex physiological phenomenon characterized by the deep automation of behavioral activity. This process is triggered exclusively when an organism repeatedly satisfies its needs in completely identical environmental conditions. As repetition continues, behavioral acts (so-called "systemquants") acquire a rigidly programmed nature.
The key mechanism of this phenomenon is that external triggering stimuli gradually lose their primary significance. The leading cause of behavior becomes an individually acquired internal program that relies entirely on consolidated memory mechanisms.
Characteristic features of stereotyped behavior:
- Loss of the orienting-exploratory component. The organism no longer needs to deploy active attention to analyze a familiar situation.
- Subconscious nature. Programs are constructed and executed primarily with the participation of subcortical mechanisms, freeing higher brain centers from routine work.
- Process synchronization. There is a highly pronounced coordination of the somatic (motor) and autonomic functions of the organism.
Experimental Basis: Ivan Pavlov's Experiments
The phenomenon of the dynamic stereotype was most clearly discovered and studied in Ivan Pavlov's laboratory. Experiments were conducted on dogs under strictly controlled conditions using the same chamber, with stimuli applied in an invariable sequence.
Signals of varying physical strength were used as conditioned stimuli: light (weak), tone (medium), and a bell (strong). Reinforcement was always an identical portion of meat-cracker powder. According to the law of strength of conditioned stimuli, the magnitude of the conditioned reflex response is directly proportional to the physical strength of the stimulus. Therefore, with equal reinforcement, the bell elicited more salivation than the light.
After many days of repeating this strict sequence, a clear ratio of secretory responses became established:
- Light: 5 drops of saliva.
- Tone: 8 drops of saliva.
- Bell: 12 drops of saliva.
Essence of the phenomenon (stress test): To prove the presence of the stereotype, researchers replaced all consecutive heterogeneous stimuli with a single, weakest one — light. The results were striking:
- Light presented in its usual place yielded 5 drops.
- Light presented in place of the tone elicited 8 drops.
- Light presented in place of the bell provoked the secretion of 12 drops.
Conclusion: The character of the response within a stereotype is determined not by the physical strength of the currently presented stimulus, but by the properties of the signal that operated at that specific time and place previously (memory mechanisms).
Adaptive Role and Disruption of the Stereotype
Any behavior is an optimal tool for survival under specific environmental conditions. All living organisms, including humans, strive to develop dynamic stereotypes because this carries essential adaptive significance—behavioral automation and enormous conservation of central nervous system resources.
Forms of behavior are divided depending on environmental conditions:
- Instinctive behavior is adequate for relatively constant conditions persisting across many generations. It is mediated primarily by subcortical structures (particularly the limbic system).
- Acquired forms of behavior are characteristic of existence in a constantly changing external environment. Here, external stimuli become signals for satisfying needs, and the process is implemented with maximum participation of the cerebral cortex.
What happens during a stereotype disruption? If, during automated activity, the intermediate or final useful result is not achieved (the situation has changed), a disruption of the stereotype occurs. At this moment, orienting-exploratory activity is immediately switched on, and dynamic cortical mechanisms are activated so the organism can reassess the situation and find a new solution.