Habituation - Characteristics of Habituation

Characteristics of Habituation

Habituation as a form of non-associative learning can be distinguished from other behavioral changes (e.g., sensory adaption, fatigue) by considering the characteristics of habituation that have been identified over several decades of research. The characteristics first described by Thompson and Spencer have recently been updated and include the following:

• Repeated presentation of a stimulus will cause a decrease in reaction to the stimulus. This characteristic is consistent with the definition of habituation as a procedure, but to confirm habituation as a process additional characteristics must be demonstrated.

• Spontaneous recovery is observed. That is, a habituated response to a stimulus recovers (increases in magnitude) when a significant amount of time (hours, days, weeks) passes between stimulus presentations. After the initial “recovery”, responding returns to its habituated level with subsequent stimulus presentations.

• "Potentiation of habituation" is observed when tests of spontaneous recovery are given repeatedly. In this phenomenon, the decrease in responding that follows spontaneous recovery becomes more rapid with each test of spontaneous recovery.

• An increase in the frequency of stimulus presentation (i.e., shorter interstimulus interval) will increase the rate of habituation and the “size” of the response decrement.

• Within a specific sensory quality (e.g., hearing), weaker stimuli presentations will elicit stronger habituation.

• Continued exposure to the stimulus after the habituated response has plateaued (i.e., show no further decrement) may have additional effects on subsequent tests of behavior such as delaying spontaneous recovery.

• Stimulus generalization and stimulus discrimination will be observed. Habituation to an original stimulus will also occur to other stimuli that are similar to the original stimulus (stimulus generalization). The more similar the new stimulus is to the original stimulus, the greater the habituation that will be observed. When a subject shows habituation to a new stimulus that is similar to the original stimulus but not to a stimulus that is different from the original stimulus, then the subject is showing stimulus discrimination. (For example, if one was habituated to the taste of lemon, their responding would increase significantly when presented with the taste of lime). Stimulus discrimination can be used to rule out sensory adaptation and fatigue as an alternative explanation of the habituation process.

• A single introduction of a different stimulus late in the habituation procedure when responding to the eliciting stimulus has declined can cause an increase in the habituated response. This increase in responding is temporary and is called "dishabituation" and always occurs to the original eliciting stimulus (not to the added stimulus). Researchers also use evidence of dishabituation to rule out sensory adaptation and fatigue as alternative explanations of the habituation process.

• Habituation of dishabituation can occur. The amount of dishabituation that occurs as a result of the introduction of a different stimulus can decrease after repeated presentation of the "dishabituating" stimulus.

• Long-term habituation. The previous nine characteristics describe behavioral changes that occur during a habituation procedure in a single session or day. Some habituation procedures appear to result in a habituation process that last days or weeks. Habituation that persists over long durations of time (i.e., show little or no spontaneous recovery) is called long-term habituation in order to distinguish it from the short-term habituation identified by the nine characteristics listed above.