Effects of telencephalic ablation on habituation of arousal responses, within and between daily training sessions in goldfish

Goldfish Carassius auratus were presented with a moving shadow stimulus at 2-min intervals and their cardiac and ventilatory responses were monitored. Normal fish, fish with their telencephalon ablated, and those with sham operations were compared for responsiveness and habituation to repeatedly presented stimuli over the 3-day test period. While all groups showed increased habituation on successive days testing, fish with their telencephalon ablated showed significantly slower response habituation within the daily test sessions when compared with the control groups. Subjects with their telencephalon ablated also showed a tendency for increased responsiveness on initial stimulus presentation and poorer retention between days of information relating to the eliciting test stimulus.     

Shock-duration reduction on the basis of interresponse times: the effect of the interresponse time limit

Rats were trained on a free-operant procedure in which the duration of randomly occurring shocks depended on the interresponse times of lever presses. Shocks of 1.6-mA intensity were delivered at random intervals with an average density of 10 shocks per min. Each shock that was delivered lasted 0.3 s as long as the interresponse times were within a preset limit. Whenever the interresponse time exceeded the limit, the shocks that were delivered lasted 1 s until the occurrence of a response that met the limit. The limit was reduced in 3-s steps from 15 s to either 6 s or 3 s, at which point 3 of the animals were exposed to an ascending series. The avoidance of long-duration shocks was highly efficient at the 15-s and 12-s limits, and it decreased at the 9-s limit. With the exception of one animal, performance was substantially worse at the 6-s limit and it deteriorated for all the animals that were exposed to the 3-s limit. The data suggest that shock-duration reduction is quite effective as negative reinforcement for avoidance but is perhaps less effective than shock-intensity reduction.     

Inter-stimulus interval and the rate of behavioural habituation

A series of 10 tone stimuli was presented to rats at intervals of 1/4, 1/2, 1, 1 1/2, 2, 2 1/2, or 3 min or 24 h. The next day a test tone was presented and the distraction to this measured. There was less habituation (i.e. greater distraction) at shorter inter-stimulus intervals, but this effect asymptoted at 2 min and thereafter there was no further increase in habituation, even with inter-stimulus intervals of 24 h. A second independent variable was the stimulus duration which did not affect the rate of habituation, nor did it interact in any way with the inter-stimulus interval.     

Stimulus Significance Effects in Habituation of the Phasic and Tonic Orienting Reflex

Phasic and tonic measures of electrodermal activity were examined in a simple habituation paradigm, using innocuous visual stimuli. Separate groups were used to investigate the effects of stimulus significance, as manipulated by instructions. One group had no stimulus-related task (indifferent group), while the other was asked to silently count the stimuli to report to the experimenter later (significant group). Prestimulus skin conductance levels were considered as measures of the arousal level at each stimulus presentation, and the subsequent electrodermal responses were taken as the phasic orienting reflex (OR) elicited by each stimulus. Changes in prestimulus arousal were taken as measures of the tonic OR to the experimental series. Marked group differences were found in both phasic and tonic components of the OR. Some, but not all, of the significance effects in the phasic OR were attributable to differences in arousal. The results are discussed in the context of theoretical accounts of the OR.     

Stimulus significance effects in habituation of the phasic and tonic orienting reflex

Phasic and tonic measures of electrodermal activity were examined in a simple habituation paradigm, using innocuous visual stimuli. Separate groups were used to investigate the effects of stimulus significance, as manipulated by instructions. One group had no stimulus-related task (indifferent group), while the other was asked to silently count the stimuli to report to the experimenter later (significant group). Prestimulus skin conductance levels were considered as measures of the arousal level at each stimulus presentation, and the subsequent electrodermal responses were taken as the phasic orienting reflex (OR) elicited by each stimulus. Changes in prestimulus arousal were taken as measures of the tonic OR to the experimental series. Marked group differences were found in both phasic and tonic components of the OR. Some, but not all, of the significance effects in the phasic OR were attributable to differences in arousal. The results are discussed in the context of theoretical accounts of the OR.     

Effects of level of arousal and type of task on bilateral skin conductance asymmetry and conjugate lateral eye movements

Several recent studies have indicated that the degree and direction of bilateral skin conductance (BSC) asymmetry and the direction of conjugate lateral eye movements (CLEMs) both index hemispheric functioning. Evidence also suggests that BSC asymmetry decreases and CLEMs become more unidirectional as level of arousal increases. Thirty-two normal adults received an habituation series of five-second tones followed by 40 questions. All stimuli were tape recorded. The questions (Schwartz, Davidson, and Maer, 1975) were grouped in four series: 10 verbal-emotional, 10 verbalnonemotional, 10 spatial-emotional, and 10 spatial-nonemotional. The order in which the four series were presented was counterbalanced across subjects. Prior to each question, subjects fixated the face of a mannequin. Sixteen subjects (high arousal) had five seconds to contemplate their answer; the remaining 16 (low arousal) had 10 seconds. Instructions for the high arousal group specified that intelligence and problem-solving ability was being tested, and that speed and accuracy were very important. Those for the low arousal group indicated casually that subjects were to ponder a series of questions. BSC levels, SC response amplitudes, and CLEMs were measured during a five-second interval following each tone or question. BSC levels were greater under the High Arousal condition. While approximately two-thirds of the subjects showed BSC asymmetry (roughly evenly divided between those with larger left and right hand responses), neither the degree nor direction of the asymmetries changed as a function of question type. While CLEM direction was more sensitive to question type under low arousal, (i.e., verbal questions resulted in predominantly right-going CLEMs and spatial questions resulted in predominantly left-going CLEMs) they tended to be stereotyped (i.e., unidirectional) under high arousal. Finally, no relationship was observed between CLEM direction and BSC asymmetry under either high or low arousal condition.     

The influence of affective factors on time perception

Several studies have suggested that both affective valence and arousal affect the perception of time. However, in previous experiments, the two affective dimensions have not been systematically controlled. In this study, standardized photographic slides rated for emotional valence and arousal were projected to two groups of subjects for 2, 4, and 6 sec. One group of subjects estimated the projection duration on an analog scale, whereas the second group of subjects reproduced the intervals by pushing a button. Heart rate and skin conductance responses were also recorded during stimulus presentation as indices of attention and arousal. Time estimation results showed neither a main effect of valence nor a main effect of arousal. A highly significant valence × arousal interaction affected duration judgments. For low-arousal stimuli, the duration of negative slides was judged relatively shorter than the duration of positive slides. For high-arousal stimuli, the duration of negative slides was judged longer than the duration of positive slides. The same interaction pattern was observed across judgment modalities. These results are interpreted in terms of a model of action tendency, in which the level of arousal controls two different motivational mechanisms, one emotional and the other attentional.     

Long-term habituation to spatial novelty in blind cave fish (Astyanax hubbsi): role of the telencephalon and its subregions

Blind cave fish, when released into a novel environment, show a typical exploratory behavior characterized by high swim speed along walls shortly after release. This behavior wanes during prolonged exposure and thus may reflect habituation to novelty. As the hippocampus of mammals, which plays a crucial role in spatial learning, is part of the telencephalon, the possible involvement of this brain structure of fish was investigated in exploratory behavior. Ablation of the whole telencephalon or bilateral removal of dorsal parts of the hemispheres reduced activity; in contrast, unilateral lesions of one hemisphere, bilateral lesions of dorsal and dorsoventral parts, and removal of olfactory bulbs increased activity. However, the time course of habituation in a novel environment remained unchanged, except for ablated animals in which there was virtually no habituation in swim speed. These data suggest that the telencephalon of fish may not participate in long-term habituation to spatial novelty but, rather, support the notion of the telencephalon being involved in generation of arousal.     

Altering Reinforcer Variety or Intensity Changes the Within-Session Decrease in Responding

Operant responding often changes systematically within experimental sessions. McSweeney, Hinson, and Cannon (1996) argued that sensitization and habituation produce within-session changes in responding. The present study tested two predictions of the sensitization–habituation explanation. In two experiments, rats pressed a lever for reinforcers delivered by a multiple variable interval 15-s variable interval 15-s schedule. In Experiment 1, the variety of reinforcers delivered during the session was manipulated by varying the percentage of programmed reinforcers replaced with qualitatively different reinforcers from 0 to 75%, in five different conditions. In Experiment 2, the intensity of the reinforcer was manipulated by varying the concentration of sucrose in the sucrose and water solution used as the reinforcer from 0 to 30%, in five different conditions. Increasing the variety or the intensity of the reinforcers slowed the within-session decrease in responding. The results are consistent with the predictions of a sensitization–habituation explanation of within-session changes in responding.     

Temporal control in rats: analysis of nonlocalized effects from short interfood intervals.

The present experiment analyzed temporal control of postreinforcement pause duration during within-session changes in the criterion for reinforcement (interfood interval, IFI). Analysis of interval-by-interval changes in the pause revealed localized and nonlocalized effects from short intervals that caused specific changes in performance. In Phase 1, rats were presented with five consecutive 15-s IFIs intercalated into a series of 60-s IFIs. The 15-s set decreased the pause in adjacent and more remote 60-s intervals. In Phase 2, two sets of 15-s intervals were intercalated. The spacing between the two sets varied so that 0, 5, 10, or 15 60-s IFIs separated the sets. The postreinforcement pause tracked all changes in the IFI duration, and the localized effect from a short set extended beyond the next interval to the next few 60-s IFIs. Effects from one set, however, did not combine with a second set: Changes in the pause after two sets were the same regardless of the spacing between sets.     

Contextual effects in duration experience

The role of contextual factors on duration estimates was investigated, employing 6 time intervals ranging from 15 to 35 sec (demarcated by the onset and termination of a display panel of lights). When compared with earlier research, the results suggest that duration estimates are affected by the context of the stimulus intervals with regard to other stimuli in the series. Specifically, those stimuli that were overestimated when they were the shortest members of the series were underestimated when they were the longest intervals of the stimulus series. In addition, a lengthening effect was observed: duration estimates increased over blocks of trials for all stimulus intervals.     

An investigation of the differential-outcomes effect within sessions

The differential-outcomes effect is manifest as more accurate performance of a delayed conditional discrimination when alternative choice responses are followed by different reinforcers than when they are followed by the same reinforcer. In Experiment 1, a differential-outcomes effect was demonstrated within sessions by signaling the duration of food access for correct responses with stimuli appearing in conjunction with the sample stimuli. The delayed matching-to-sample performance of 5 pigeons was more accurate when green choice responses (matching a green sample) were followed by 3.5-s food access and red choice responses (matching a red sample) were followed by 0.5-s food access (different-outcome trials) than when the correct choice responses were both followed by 1.5-s reinforcers (same-outcome trials). In Experiment 2, the acquisition of this differential-outcomes effect was characterized by a progressive decrease in rate of forgetting on different-outcome trials and no change in rate of forgetting on same-outcome trials. In addition, accuracy at the shortest delay intervals for both different-outcome and same-outcome trials increased over acquisition, but to a greater extent for different-outcome trials. These data suggest that both memorial and attentional (time-dependent and time-independent) factors contribute to the differential-outcomes effect.     

Exploring the mechanism of dishabituation

In this study we explored elicitation and habituation of the orienting reflex (OR) in the context of indifferent and significant stimuli, particularly aiming to clarify the mechanism driving dishabituation. An in-depth analysis of the mechanisms of electrodermal habituation and dishabituation was conducted, focusing on the role of state measures as determinants of the phasic response profile. Twenty-four young adult participants completed an auditory dishabituation task while electrodermal activity was recorded. Participants listened to a series of 10 innocuous tones of the same frequency (standards), followed by a deviant tone of a different frequency, and succeeded by 2-4 tones of the same frequency as the initial 10 stimuli. All stimuli had a random stimulus onset asynchrony of 5-7 s. Participants completed an indifferent condition in which there was no task in relation to the stimuli, and a significant condition where instruction was given to count the stimuli silently; order was counterbalanced between participants. As predicted, both skin conductance responses (SCRs) and skin conductance levels (SCLs) were larger for the significant than the indifferent condition. The initial phasic ORs were dependent on pre-stimulus arousal level, and there were significant decreases in both SCR and SCL over the first 10 standards in both conditions. Phasic response recovery was apparent to the deviant stimulus, and dishabituation to the following standard stimulus; both effects were enhanced in the significant condition. Sensitisation was apparent in SCL following the initial and deviant stimuli, but the extent of this was confounded with incomplete resolution of the preceding phasic OR in the significant condition. In the indifferent condition, dishabituation was independent of deviant-related sensitisation; this could not be tested in the significant condition. These findings suggest that dishabituation is not a process of sensitisation, but rather, a disruption of the habituation process.     

Effects of stimulus duration and intensity on the rate and specificity of behavioural habituation

Tone stimuli were presented to rats once per day until habituation was reached. Neither the duration nor the intensity of the stimulus affected the rate of habituation. Habituation was specific to both these stimulus parameters as shown by the distraction produced by either an increase or a decrease in the original stimulus value. It is suggested that some of the discrepancies in the literature might be resolved if a distinction is drawn between habituation of orienting responses and the decrement of more specific responses.     

Protection from premature habituation requires functional mushroom bodies in Drosophila

Diminished responses to stimuli defined as habituation can serve as a gating mechanism for repetitive environmental cues with little predictive value and importance. We demonstrate that wild-type animals diminish their responses to electric shock stimuli with properties characteristic of short- and long-term habituation. We used spatially restricted abrogation of neurotransmission to identify brain areas involved in this behavioral response. We find that the mushroom bodies and, in particular, the α/β lobes appear to guard against habituating prematurely to repetitive electric shock stimuli. In addition to protection from premature habituation, the mushroom bodies are essential for spontaneous recovery and dishabituation. These results reveal a novel modulatory role of the mushroom bodies on responses to repetitive stimuli in agreement with and complementary to their established roles in olfactory learning and memory.     

Time,change, and motion: The effects of stimulus movement on temporal perception

The effects of stimulus motion on time perception were examined in five experiments. Subjects judged the durations (6–18 sec) of a series of computer-generated visual displays comprised of varying numbers of simple geometrical forms. In Experiment 1, subjects reproduced the duration of displays consisting of stationary or moving (at 20 cm/sec) stimulus figures. In Experiment 2, subjects reproduced the durations of stimuli that were either stationary, moving slowly (at 10 cm/sec), or moving fast (at 30 cm/sec). In Experiment 3, subjects used the production method to generate specified durations for stationary, slow, and fast displays. In Experiments 4 and 5, subjects reproduced the duration of stimuli that moved at speeds ranging from 0 to 45 cm/sec. Each experiment showed that stimulus motion lengthened perceived time. In general, faster speeds lengthened perceived time to a greater degree than slower speeds. Varying the number of stimuli appearing in the displays had only limited effects on time judgments. Other findings indicated that shorter intervals tended to be overestimated and longer intervals underestimated (Vierordt’s law), an effect which applied to both stationary and moving stimuli. The results support a change model of perceived time, which maintains that intervals associated with more changes are perceived to be longer than intervals with fewer changes.     

Neonatal auditory habituation and state change

Groups of newborn babies were exposed to various series of 90 dB SPL noiseband stimuli or to simulated (control) stimuli, while their heart rates (HR) and states of behavioural arousal were monitored. In general the response to stimulation was an accelerative HR change which tended to decrease with repeated stimulation. This seemed to provide evidence of habituation to the auditory stimuli. However, the HR response to sound depended on prestimulus HR and on state, and, when these effects were removed by regression techniques, the progressive decrease in evoked HR with repeated stimulation disappeared, apart from the first few trials. This implied that there was HR habituation to the initial stimuli, but not subsequently, when the apparent HR “habituation” reflected progressive endogenous state changes.     

Effects of signaled versus unsignaled delay of reinforcement on choice

Pigeons chose between 5-s and 15-s delay-of-reinforcement alternatives. The first key peck to satisfy the choice schedule began a delay timer, and food was delivered at the end of the interval. Key pecks during the delay interval were measured, but had no scheduled effect. In Experiment 1, signal conditions and choice schedules were varied across conditions. During unsignaled conditions, no stimulus change signaled the beginning of a delay interval. During differential and nondifferential signal conditions, offset of the choice stimuli and onset of a delay stimulus signaled the beginning of a delay interval. During differential signal conditions, different stimuli were correlated with the 5-s and 15-s delays, whereas the same stimulus appeared during both delay durations during nondifferential signal conditions. Pigeons showed similar, extreme levels of preference for the 5-s delay alternative during unsignaled and differentially signaled conditions. Preference levels were reliably lower with nondifferential signals. Experiment 2 assessed preference with two pairs of unsignaled delays in which the ratio of delays was held constant but the absolute duration was increased fourfold. No effect of absolute duration was found. The results highlight the importance of delayed primary reinforcement effects and challenge models of choice that focus solely on conditioned reinforcement.     

The sensitization of humor responses to cartoons

It was hypothesized that a humor response to a cartoon in a series depends upon arousal or increased salience, both of which may be produced by preceding cartoons. A humor response, however, should eventually decline owing to habituation. Three experiments were conducted in order to determine if responding to cartoons with the same theme depends upon the cartoon's serial position. Facial responses and ratings of funniness increased over the first few cartoons, reflecting the effect of arousal or salience. It appears that the initial cartoons make the person more sensitive to later cartoons. A downward trend in responding was more apparent for facial responses than for funniness ratings. The evidence for habituation was weak, however, and did not seem occur to the experimenter-defined cartoon theme. Cartoons even representing the same theme may be too variable to permit habituation. It was suggested that cartoon researchers be aware of the effect of a cartoon's serial position on humor responses.The investigators would like to thank Michael Davis, Michael Mullins, and Elizabeth Weaver for their assistance in data collection and analyses.     

Discrimination by newborns of the intensity, frequency and temporal characteristics of auditory stimuli

The ability of 3- to 5-day-old neonates to discriminate between auditory stimuli, in terms of each of the dimensions of intensity, pitch and time, was studied using heart-rate responses in a habituation paradigm. For each of the dimensions a survey of the literature failed to provide results which could be used as the basis for later work involving auditory patterns. Further analysis of an earlier experiment (Stratton, 1970 a) involving stimuli at 80, 85 and 90 db showed that louder stimuli evoked larger initial responses and more rapid habituation. From the same experiment it was found that a change of pitch produced dishabituation as early as the 10th trial. There are reasonable grounds for attributing the increased response to the frequency characteristics rather than a change in the perceived intensity of the stimuli. Previous experiments suggested that fixed inter-stimulus intervals tended to produce anticipatory heart-rate changes and modify the magnitude and latency of the response. Two experiments designed specifically to examine temporal phenomena revealed time-linked behaviour. In both experiments acceleratory responses occurred at the first stimulus omission of a fixed-interval series. Not all of the subjects showed this effect, and in both experiments, only the subjects who failed to respond to the first stimulus presentation responded to stimulus omission. The findings are discussed in relation to general issues of neonatal psychophysiology, and it is concluded that neonates can discriminate in each of the auditory dimensions, but that preliminary work involving patterns should concentrate on varying pitch and intensity.