Latent Inhibition

Latent Inhibition

Latent inhibition (LI) is a technical term used in Classical conditioning (Pavlovian reinforcement) that refers to the natural tendency to tune out familiar stimuli. Individuals take longer to become aware of common stimuli than novel ones. It is ‘a measure of reduced learning about a stimulus to which there has been prior exposure without any consequence.’ Latent inhibition occurs when voluntarily trying to ignore an ongoing sound (like an air conditioner) or not hear the conversation of others.

This tendency to disregard or even inhibit formation of memory (by preventing associative learning of observed stimuli) is an unconscious response, and is assumed to prevent sensory and cognitive overload. Latent inhibition is observed in many species, and is believed to be an integral part of learning, enabling an organism to interact successfully in an environment.

LI is demonstrated when a previously unattended stimulus is less effective in a new learning situation than a novel stimulus. The term dates back to Lubow and Moore (1959). The effect is ‘latent’ in that it is not exhibited in the stimulus pre-exposure phase, but rather in the subsequent test phase. ‘Inhibition,’ here, simply connotes that the effect is expressed in terms of relatively poor learning. The LI effect is extremely robust, appearing in all mammalian species that have been tested and across many different learning paradigms, thereby suggesting some adaptive advantages, such as protecting the organism from associating irrelevant stimuli with other, more important, events.

LI is affected by many factors, one of the most important of which is context. In virtually all LI studies, the context remains the same in the stimulus pre-exposure and test phases. However, if context is changed from the pre-exposure to the test phase, then LI is severely attenuated. The context-dependency of LI plays major roles in all current theories of LI, and in particular to their applications to schizophrenia. When LI occurs, working-memory is inundated with experimentally familiar but phenomenally novel stimuli, each competing for the limited resources required for efficient information processing. This description fits well with the positive symptoms of schizophrenia, particularly high distractibility.

In addition to LI illustrating a fundamental strategy for information processing and providing a useful tool for examining attentional dysfunctions in pathological groups, research has also suggested techniques that may be efficacious in the prophylactic treatment of certain fears and phobias. Of popular interest, several studies have attempted to relate LI to creativity.

In summary, the basic LI phenomenon represents some output of a selective attention process that results in learning to ignore irrelevant stimuli. It has become an important tool for understanding information processing in general, as well as attentional dysfunctions in schizophrenia, and it has implications for a variety of practical problems.

Most people are able to ignore the constant stream of incoming stimuli, but this capability is reduced in those with low latent inhibition. Low latent inhibition seems to cause one person to be more distractible than another. It is hypothesized that a low level of latent inhibition can cause either psychosis or a high level of creative achievement or both, which is usually dependent on the individual’s intelligence. Those of above average intelligence are thought to be capable of processing this stream effectively, enabling their creativity. Those with less than average intelligence, on the other hand, are less able to cope, and as a result are more likely to suffer from mental illness and sensory overload. High levels of the neurotransmitter dopamine (or its agonists) in the brain have been shown to decrease latent inhibition.

Low latent inhibition is not a mental disorder but an observed personality trait, and a description of how an individual absorbs and assimilates data or stimuli. Furthermore, it does not necessarily lead to mental disorder or creative achievement—this is, like many other factors of life, a case of environmental and predispositional influences, whether these be positive (e.g., education) or negative (e.g., abuse) in nature. There is at least some evidence to suggest that one can reduce one’s latent inhibition, contributing to more distractibility and sensory overload, through the use of Cannabis.

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