Habituation and other Forms of Stimulus Learning
Chapter 2
I. THE ORIENTING RESPONSE
A. An orienting response (OR) is elicited when a novel or unexpected stimulus is presented to an organism.
B. Physiological and behavioral reactions of OR--startle response, flight response, increased arousal
C. Novelty is not only factor responsible for ORs. Stimulus intensity& situational cues play role, too. Also possible for familiar stimuli to elicit an OR.
II. HABITUATION
A. Habituation is the decrease in ORs (and other reactions) to a stimulus that is repeatedly presented.
Unique form of learning --LESS responding over time, not more.
Habituation applies only to neutral stimuli, not intense or painful ones.
Habituation occurs across the phylogenetic scale,
from snails to humans.
An example in rats
Below is an example in human infants
B. Habituation has been studied using a variety of measurements
C. . Several parametric features of habituation:
1. Frequency
2. Spontaneous Recovery example in rats
3. Repeated Habituations
4. Spacing
5. Dishabituation example in rats
6. Generalization
III. EXPLANATIONS OF HABITUATION
A. Some argue that habituation isn’t learning at all.
1. Occurs as a result of sensory adaptation, as sense receptors become less sensitive as a function of repeated stimuli presentations.
2. Effector fatigue occurs in experimental situations, one’s response system becomes depleted, causing a reduction in responding.
3. Sensory adaptation and effector fatigue are more likely to explain habituation when many (greater than 20) and highly intense stimuli are used.
B. Other explanations support learning processes. These deal with physiological and cognitive approaches, which typically compare habituation effects to sensitization (response increases over time).
1. Dual-Process theory--one of the neuroscience explanations
2. Kandel’s research with Aplysia also illustrates the physiological nature of habituation.
3. Cognitive explanations of habituation tend to concern memory representation of the stimulus
IV. PERCEPTUAL LEARNING
A. Perceptual Learning suggests that we can learn more about a stimulus when it is easily perceived, and increased experience with stimuli allows such enhanced perceptions to occur.
B. Factors playing role in perceptual learning.
1. Presenting + and - instances of stimulus categories leads to effective understanding of items.
2. Perception of difficult discriminations can be facilitated by training first on easier tasks.
3. General understanding of stimuli does not necessarily require intent, understanding how to discriminate between similar stimuli demands cognitive effort.
V. OTHER EFFECTS OF STIMULUS EXPOSURE
A. Habituation, although a common effect, is not the only outcome of stimulus exposure.
B. The mere exposure effect also arises from stimulus exposure, and involves the demonstration of an increased level of positive affect directed towards a stimulus as a result of prior exposure to that stimulus.
C. Initial exposure to unfamiliar stimuli can also lead to neophobia--involves fear of new foods, tastes, or odors. Tends to decline with experience.
D. Conscious processing of stimuli has also been shown to not be entirely critical to obtaining the mere exposure effect, and Kunst-Wilson and Zajonc’s work shows that mere exposure can be generated under subliminal conditions.
E. Priming has also been shown to facilitate information processing, although it involves a single presentation of a stimulus, not the increased number of presentations involved to produce the mere exposure effect.
F. Certain types of stimulus exposure can also lead to potentiated startle, which occurs when a startle response is magnified because a startling stimulus is combined with an existing arousal state.
V. APPLICATIONS
A. Habituation can be observed in many real-world settings.
B. Stimulus exposures have been used in the treatment of anxiety and phobias.
1. Emotional flooding--therapists use controlled exposure to feared stimuli, to reduce the fear provoked by the situation.
2. Virtual Reality exposure therapy has also been utilized within this context; computer-generated images are projected to patients in an attempt to reduce anxiety.
3. Some scientists, however, advocate maximal arousal and actual contact with the feared stimulus in order to treat one’s phobia.
4. Some patients are helped by these procedures, but total remission is rare.