Habituation and dishabituation of female sexual arousal

Measures of subjective and physiological sexual arousal were taken within a session while women either viewed the same segment of erotic film on many occasions or employed the same sexual fantasy over a number of trials. For both film and fantasy there were significant reductions in subjective sexual arousal and average pulse amplitude during the course of repeated erotic stimulation. Subsequent presentation of novel erotic stimuli led to recovery in sexual arousal. Bases for habituation and dishabituation of female sexual arousal are discussed.     

Habituation of cognitive and physiological arousal and social anxiety

This study examined differences in habituation between high and low socially anxious Ss. Participants gave three impromptu speeches, each separated by a brief rest interval. Skin conductance and heart rate were monitored during the speeches. Following each speech participants completed self-ratings of nervousness, heart rate, and palmar sweat activity as well as a modified Social Interaction Self Statement Test. Low anxious controls showed significant reduction of negative expectations and self-reported nervousness, heart rate, and sweat activity across the three trials. Actual heart rate of low-anxious subjects also decreased significantly across trials. In contrast, high anxious subjects did not evidence significant decreases in any of the above measures of anxiety and stress across the three trials. Skin conductance measures increased across trials for both groups, but increased more for the high anxious group than low-anxious controls. Results indicate that high anxiety participants are slow to decrease cognitive and autonomic responsiveness to stressful social situations.     

Habituation of the hiding response to cat odor in rats (Rattus norvegicus)

Cat odor-induced hiding was examined in rats (Rattus norvegicus) using an apparatus with a "hide box" at one end and a piece of a worn cat collar at the other end. Rats spent most of their time hiding on exposure to the cat collar, but this response gradually habituated over repeated daily exposures. Hiding was reversed by administering the anxiolytic drug midazolam (0.375 mg/kg). Rats showed increased anxiety on the elevated plus-maze after exposure to the collar. This response was absent in habituated rats, suggesting that habituation of hiding reflects decreased odor-induced anxiety. It was established that rats located in the hide box of the apparatus might not have detected the odor of the cat collar placed at the other end of the apparatus. This implies that habituation occurs after relatively modest levels of odor exposure. Overall, the results cast some doubt on claims that predatory odors in rats are akin to phobic stimuli in humans.     

Habituation of the visual orienting response in young children1, 2

The eye tracks of 29 children (aged 2-7 years) were recorded by a reflection eye camera while they were looking ata4by 4 matrix of 16 white geometric shapes. When a circle suddenly changed to red, the children immediately looked at it for two-thirds of the presentation time, a reading which was 16 times the initial level before this novel color was introduced. With repeated presentations of the novel red circle display, progressively fewer fixations fell on the red circle. After 20 trials, this habituation was incomplete, and the red circle was still drawing six times the initial amount of looking found on the original white circle. Ss were apparently relatively slow to form a neural representation of the visual environment due to the wide range of choices in the original display. The age of the children had no monotonic effect on the high, and virtually equal, initial visual concentration, nor on the rate at which habituation occurred. An interesting contrast, therefore, appeared between these data and the marked age effects noted by others in the recognition of letter-like shapes. Unlike recognition tasks, orienting and habituation need a minimum of stimulus interpretation. Children, even as young as 2 years, have demonstrated a remarkable efficiency in these processes of orienting and habituation to novelty.     

Habituation in the rat fetus

Rat fetuses exhibit motor and cardiac responses to chemosensory stimulation on Days 20 and 21 of gestation. The first experiment demonstrated that fetuses exhibit an increase in overall motor activity and decrease in heartrate in response to an initial intraoral infusion of a lemon solution. After a series of nine exposures, however, fetuses no longer exhibit motor or cardiac responses to lemon infusion, suggesting the existence of a habituation-like process. Responsiveness recovers spontaneously following a 3-to 9-min period without stimulation. In a second experiment, a dishabituation treatment was administered to distinguish habituation, which is a centrally mediated decrement in response, from effector fatigue, sensory adaptation, and other peripheral mechanisms that can result in reduced responsiveness. A single infusion of mint following a series of nine lemon exposures was effective in reinstating fetal motor responses to lemon on both Days 20 and 21, but reinstated cardiac responses only on Day 21. Rat fetuses habituate to repeated chemosensory stimulation, suggesting the utility of the habituation paradigm in measuring CNS development during the perinatal period.     

Habituation in songbirds

Songbirds respond to initial playback of a recorded conspecific song in numerous ways, from changes in gene expression in the brain to changes in overt physical activity. When the same song is presented repeatedly, responses have been observed to habituate at multiple levels: molecular, cellular and organismal. Core criteria of habituation have been established at each level, although in no case have all the formal parameters been rigorously measured. At the level of overt behavior, classical field studies showed that territorial birds respond to the song of a potential challenger with a variety of behaviors, and many (but not all) of these behaviors decline with repeated stimulus presentation. More recent laboratory studies have defined analogous responses to song presentation in the zebra finch (Taeniopygia guttata), the dominant species in current molecular and neurobiological research and one that does not use song for territorial defense. Studies in the zebra finch have also demonstrated activation followed by habituation of responses measured at both electrophysiological and molecular (gene expression and signal transduction) levels. In all cases, habituation is specific for a very particular stimulus – an individual song presented in a particular context. There are strong correlations between habituation measurements made at these different levels, but some dissociations have also been observed, implying that molecular, electrophysiological and behavioral habituations are not equivalent manifestations of a single core process.     

Changes in the magnitude of the eyeblink startle response during habituation of sexual arousal

Modulation of the startle response was used to examine emotional processing of sexual stimulation across trials within a session. Eyeblink startle was elicited by a probe (burst of intense white noise) presented intermittently while men were viewing an erotic film segment. Repeated display of the film segment resulted in a progressive decrease in sexual arousal. Habituation of sexual arousal was accompanied by a reduction over trials in the extent the men felt absorbed when viewing the erotic stimulus and by an increase over trials in the magnitude of the eyeblink startle response. Replacing the familiar stimulus by a novel erotic stimulus increased in sexual arousal and absorption and reduced startle (novelty effect), while dishabituation was evident for all three response measures when the familiar stimulus was reintroduced. This pattern of results indicates that with repeated presentation an erotic stimulus is experienced not only as less sexually arousing but also as less appetitive and absorbing. The question of whether habituation of sexual arousal is mediated by changes in attentional and affective processing over trials is discussed, as are clinical contexts in which eyeblink startle can be used in studying aspects of sexual functioning.     

Habituation in the rat fetus.

Rat fetuses exhibit motor and cardiac responses to chemosensory stimulation on Days 20 and 21 of gestation. The first experiment demonstrated that fetuses exhibit an increase in overall motor activity and decrease in heartrate in response to an initial intraoral infusion of a lemon solution. After a series of nine exposures, however, fetuses no longer exhibit motor or cardiac responses to lemon infusion, suggesting the existence of a habituation-like process. Responsiveness recovers spontaneously following a 3- to 9-min period without stimulation. In a second experiment, a dishabituation treatment was administered to distinguish habituation, which is a centrally mediated decrement in response, from effector fatigue, sensory adaptation, and other peripheral mechanisms that can result in reduced responsiveness. A single infusion of mint following a series of nine lemon exposures was effective in reinstating fetal motor responses to lemon on both Days 20 and 21, but reinstated cardiac responses only on Day 21. Rat fetuses habituate to repeated chemosensory stimulation, suggesting the utility of the habituation paradigm in measuring CNS development during the perinatal period.     

Habituation assessment in infancy

Infant-control habituation methodology, although serving the research community well, has never been carefully analyzed. A main use is to equate infants in their level of habituation prior to experimental manipulations in a posthabituation phase. When studied analytically and with simulation, it is found to have serious difficulties. It inadvertently recruits infants with large variations in performance while discriminating against those with less variable performance. For nonhabituating infants, its Type I error rates can approach 1. A model-based nonlinear regression framework is proposed, which, because of large individual differences in infants, takes as the unit of analysis the individual infant. It is shown to be more powerful and efficient than existing procedures and can offer practical and theoretical benefits.     

The pupillary response as an indicator of arousal and cognition

Psychological research on the pupillary response since 1960 has focused on an arousal interpretation and a cognitive interpretation. Experiment 1 was an attempt to manipulate some arousal factors while controlling the cognitive demands of the task. Pupil size was cinematographically recorded while subjects who had different degrees of reported fear of snakes listened to passages describing imagined interactions with a snake in different proximities. There was also a set of control passages that made no mention of snakes but were otherwise semantically and syntactically identical to the aversive passages. The pupillary response showed no influence of the arousal manipulations, but rating and behavioral data indicated that the arousal variables had been effective. The cognitive demands of the task were clearly indicated by the pupillary response. In Experiment 2 two types of tasks were used: one that employed both arousal (incentive) and cognitive factors and another that had an arousal manipulation (threat of shock) but no explicit cognitive demands. The pupil response was recorded as well as heart rate, skin conductance, and EMG. The pupillary response showed an effect of the arousal manipulations only when cognitive demands were minimal. The results of both experiments are consistent with the view that cognitive demands take priority over arousal factors in affecting the pupillary response. Heart rate did show arousal effects that were not preempted by cognitive demands.     

Air-puff-elicited startle: Habituation over trials and measurement of a hypothetical emotional response

In the first of two experiments, it was demonstrated that an air puff elicited a reliable startle reflex in rats which showed no habituation over 50 trials. In the second study an attempt was made to measure an emotional response by recording startle reactions to the air puff during presentation of a presumed fear-eliciting CS. It was concluded that the air-puff-elicited startle reflex can be employed as an indirect measure of a hypothetical emotional response.