Dynamic stereotype

Formation mechanism and characteristics

A dynamic stereotype is a complex physiological phenomenon, the essence of which lies in the profound automation of behavioral activity. This process is triggered exclusively when the organism repeatedly satisfies its needs in absolutely uniform environmental conditions. As repetition continues, behavioral acts (so-called "systemquants") acquire the character of rigid programming.

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 stereotypical behavior:

1. Loss of the orienting-investigatory component. The organism no longer needs to engage active attention to analyze a familiar situation.
2. Subconscious nature. Programs are built and implemented primarily with the participation of subcortical mechanisms, freeing higher brain regions from routine work.
3. Synchronization of processes. There is a maximally pronounced coordination of the body's somatic (motor) and autonomic functions.

Experimental basis: I.P. Pavlov's experiments

The phenomenon of the dynamic stereotype was most clearly discovered and studied in I.P. Pavlov's laboratory. Experiments were conducted on dogs under strictly controlled conditions: the same chamber was used, and stimuli were delivered in an invariable sequence.

Signals of varying physical strength were used as conditioned stimuli: light (weak), tone (medium), and bell (strong). Reinforcement was always an identical portion of meat-biscuit powder. According to the law of strength of conditioned stimuli, the magnitude of the conditioned reflex response is directly proportional to the impact strength. Therefore, with identical reinforcement, the bell elicited more saliva than the light.

Upon multi-day repetition of this strict sequence, a clear ratio of secretory responses was 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 sequential heterogeneous stimuli with a single weakest one — light. The results were striking:

1. Light in its usual place yielded 5 drops.
2. Light turned on in place of the tone elicited 8 drops.
3. Light turned on in place of the bell provoked the secretion of 12 drops.

Conclusion: The nature of the response within the stereotype is determined not by the physical strength of the stimulus presented at the given moment, but by the properties of the signal that acted at this time and in this place previously (memory mechanisms).

Adaptive role and breakdown of the stereotype

Any behavior is an optimal tool for survival in certain living conditions. All living organisms, including humans, strive to develop dynamic stereotypes, as this carries a crucial adaptive significance — the automation of actions and colossal conservation of central nervous system resources.

Forms of behavior are divided depending on environmental conditions:

• Instinctive behavior is adequate for relatively unchanged conditions persisting over many generations. It is ensured primarily by subcortical structures (in particular, 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 maximal participation of the cerebral cortex.

What happens during a stereotype breakdown? If the stage or final useful result is not achieved during automated activity (the situation has changed), a so-called stereotype breakdown occurs. At this moment, orienting-investigatory activity is immediately switched on and dynamic cortical mechanisms are activated so that the organism can reassess the situation and find a new solution.

Briefly: answers to topical questions

Class and exam questions

What else to study on this topic

• Law of strength of conditioned stimuli
• The role of the limbic system in instinctive behavior
• Orienting-investigatory reflex and active attention
• Memory mechanisms in the formation of conditioned reflexes
• Interaction of the cortex and subcortical structures in acquired behavior

Other topics in the section "Inhibition of Conditioned Reflex Activity"

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