Change In Stimulus Conditions Research Articles

Further evidence of renewal in automatically maintained behavior.

Renewal is a relapse phenomenon that refers to the recurrence of a previously reduced behavior following a change in stimulus conditions. Muething et al. (2022) examined the phenomenology of renewal among individuals with automatically maintained challenging behavior treated at an outpatient clinic. We replicated their findings by retrospectively examining renewal across various topographies of automatically maintained behavior treated at an inpatient hospital, and we extended their work by also examining differences across subtypes of automatically maintained self-injurious behavior. The prevalence of renewal was comparable to that observed by Muething et al., supporting the notion that automatically maintained challenging behavior is susceptible to relapse phenomena. Furthermore, renewal was twice as likely to occur for individuals with Subtype 2 versus Subtype 1 self-injurious behavior, providing additional evidence of behavioral differentiation between subtypes. Our findings suggest that even after apparent stability in treatment, practitioners should remain vigilant for the recurrence of automatically maintained behavior during generalization.

Evaluating Compulsive‐Like Drug‐Taking Using Signaled and Unsignaled Footshock Procedures in Male and Female Rats Self‐Administering MDPV

A subset of rats that self‐administer synthetic cathinones, such as 3,4‐methylenedioxypyrovalerone (MDPV), develop high levels of drug intake and patterns of responding similar to the compulsive, binge‐like patterns of cathinone (e.g., “bath salts”) use reported in humans. Though high‐responder rats exhibit some behaviors thought to be related to substance use disorder, the effects of punished responding in these rats were unknown. These studies evaluated whether (1) high‐responder rats were less sensitive to footshock‐punished responding than low‐responder rats using both unsignaled and signaled footshock procedures; (2) whether sensitivity to footshock was dependent on the self‐administered dose of MDPV. Inhibition curves for unsignaled footshock (0.05‐0.9 mA, increasing across sessions) were evaluated in forty adult Sprague Dawley rats self‐administering 0.01, 0.032, and 0.1 mg/kg/infusion MDPV under a FR5 schedule of reinforcement; footshocks were paired with ~50% of drug infusions. Rats were then trained on a signaled footshock procedure, in which a change in stimulus conditions signaled that the next infusion would be paired with a footshock (intensities individualized to each rat’s IC50). Rats could avoid this footshock by withholding responding for 30‐sec. After rats learned the signaled shock procedure, inhibition curves were generated using a range of footshock intensities (0.05‐0.9 mA). High‐ and low‐responder rats were similarly sensitive to unsignaled punishment by footshock (mean IC50s‐ high‐responders: 0.30mA; low‐responders: 0.36mA). However, high‐responder rats (mean: 45mA) received significantly more total current than low‐responder rats (mean: 18mA). Compared to low‐responder rats, high‐responder rats respond more in the presence of the signal indicating impending shock and avoid a smaller proportion of shocks. This suggests high‐responder rats may be less able to adapt their behavior in response to a stimulus associated with punishment. These studies suggest that the high levels of drug‐taking observed in the high‐responder rats reflects a compulsive‐like pattern of responding, which may be related to continued use despite adverse consequence, a DSM symptom of substance use disorder.

Renewal and resurgence of severe problem behavior in an intensive outpatient setting: Prevalence, magnitude, and implications for practice

AbstractFollowing successful behavioral treatment in which problem behavior is reduced, problem behavior sometimes reemerges as a function of changes in stimulus conditions (i.e., renewal) or the worsening of reinforcement conditions for an appropriate alternative response (i.e., resurgence). Extant research suggests that both renewal and resurgence may be relatively prevalent phenomenon in a variety of clinical settings. The purpose of the present study was to replicate and extend extant research quantifying the prevalence and magnitude of renewal (Experiment 1) and resurgence (Experiment 2) in an intensive outpatient clinic via retrospective consecutive controlled case series (CCCS; Hagopian, 2020). Findings from the current study—which represents the largest sample to date investigating relapse in applied settings—suggest that both renewal and resurgence are relatively common phenomenon and occur in the majority of treatment applications. Based on our findings (and emerging research in this area), we provide recommendations for practitioners to mitigate the occurrence of renewal and resurgence in clinical contexts.

A review of investigations of operant renewal with human participants: Implications for theory and practice.

Operant renewal is the recurrence of a previously eliminated target behavior as a function of changing stimulus contexts. Renewal as a model of treatment relapse in humans suggests that a change in stimulus conditions or context is sufficient to produce relapse of a previously eliminated maladaptive behavior. The extent to which general findings from operant renewal studies involving nonhuman animal subjects are supported by relapse studies involving human participants is unknown. We conducted a systematic review of studies demonstrating or mitigating operant renewal in human participants in peer-reviewed studies found in PsycINFO, ERIC, PubMed, and Scopus between 1980 and 2019. We identified 12 studies involving 61 participants and 93 cases of operant renewal. We coded descriptive data on participant and study characteristics and calculated summary statistics. Results indicated that the renewal effect was a robust phenomenon, supported by demonstrations in both clinical and human-laboratory studies, and across a variety of variables and experimental preparations. However, there were relatively few studies involving human participants that attempted to reduce or eliminate renewal of clinically meaningful behavior. We discuss variables relevant for studying renewal in socially meaningful contexts, practical limitations of observing the renewal effect in real-world settings, implications for theoretical models of renewal, and identify barriers to methodology unique to human participants. We provide directions for future research related to implementing and translating nonhuman animal studies of renewal to applied settings.

Effects of pupil center shift on ocular aberrations.

We investigated effects of pupil shifts, occurring with changes in luminance and accommodation stimuli, on refraction components and higher-order aberrations. Participants were young and older groups (n = 20; 22 ± 2 years; age range, 18-25 years; and n = 19, 49 ± 4 years, 45-58 years, respectively). Aberrations/refractions at 4- and 3-mm diameters were compared between centered and decentered pupils for low (background, 0.01 cd/m(2), 0 diopters [D]), and high (6100 cd/m(2), 4 or 6 D) stimuli. Decentration was the difference between pupil centers for low and high stimuli. Clinical important changes with decentration were: M at ± 0.50 or ± 0.25 D, J180 and J45 at ± 0.25 or ± 0.125 D, HORMS at ± 0.05 μm, C(3, 1) at ± 0.05 μm, and C(4, 0) at ± 0.05 μm. Because of small pupil shifts in most participants (mean 0.26 mm), there were few important changes in most refraction components and higher-order aberration terms. However, M changed by >0.25 D for a third of participants with 4-mm pupils. When determining refractions from second to sixth order aberration coefficients, the more stringent criteria gave 76/534 (14%) possible important changes. Some participants had large pupil shifts with considerable aberration changes. Comparisons at the high stimulus were possible for only 11 participants because of small pupils. When refractions were determined from second order aberration coefficients only, only 35 (7%) had important changes for the more stringent criteria. Usually pupil shifts with changes in stimulus conditions have little influence on aberrations, but they can with high shifts. The number of aberrations orders that are considered as contributing to refraction influences the proportion of cases that might be considered clinically important.

Choice, changing over, and reinforcement delays.

In three experiments, pigeons were used to examine the independent effects of two normally confounded delays to reinforcement associated with changing between concurrently available variable-interval schedules of reinforcement. In Experiments 1 and 2, combinations of changeover-delay durations and fixed-interval travel requirements were arranged in a changeover-key procedure. The delay from a changeover-produced stimulus change to a reinforcer was varied while the delay between the last response on one alternative and a reinforcer on the other (the total obtained delay) was held constant. Changeover rates decreased as a negative power function of the total obtained delay. The delay between a changeover-produced stimulus change had a small and inconsistent effect on changeover rates. In Experiment 3, changeover delays and fixed-interval travel requirements were arranged independently. Changeover rates decreased as a negative power function of the total obtained delay despite variations in the delay from a change in stimulus conditions to a reinforcer. Periods of high-rate responding following a changeover, however, were higher near the end of the delay from a change in stimulus conditions to a reinforcer. The results of these experiments suggest that the effects of changeover delays and travel requirements primarily result from changes in the delay between a response at one alternative and a reinforcer at the other, but the pattern of responding immediately after a changeover depends on the delay from a changeover-produced change in stimulus conditions to a reinforcer.

Physiological studies of the precedence effect in the inferior colliculus of the cat. I. Correlates of psychophysics.

The precedence effect (PE) is experienced when two spatially separated sounds are presented with such a brief delay that only a single auditory image at or toward the location of the leading source is perceived. The responses of neurons in the central nucleus of the inferior colliculus (ICC) of cats were studied using stimuli that are known to elicit the PE, focusing on the effects of changes in stimulus conditions that a listener might encounter in a natural situation. Experiments were conducted under both free-field (anechoic chamber) and dichotic (headphones) conditions. In free field, the PE was simulated by presenting two sounds from different loudspeakers with one sound delayed relative to the other. Either click or noise stimuli (2- to 10-ms duration) were used. Dichotically, the same conditions were simulated by presenting two click or noise pairs separated by an interstimulus delay (ISD) with interaural time differences (ITDs) imposed separately for each pair. At long ISDs, all neurons responded to both leading and lagging sources as if they were delivered alone. As the ISDs were shortened, the lagging response became suppressed. The ISD of half-maximal suppression varied considerably within the population of neurons studied, ranging from 2 to 100 ms, with means of 35 and 38 ms for free field and dichotic conditions, respectively. Several correlates of psychophysical findings were observed in ICC neurons: suppression was usually stronger with lower overall stimulus level and longer duration stimuli. Suppression also was compared along the azimuth and elevation in free field by placing the lagging source at (0 degree,0 degree), which is common to both axes, and the leading sources at locations along either plane that generated similar discharge rates. All neurons that showed suppression along the azimuth also did so in the elevation. In addition, there was a high correlation in the ISD of half-maximal suppression along the two planes (r = 0.87). These findings suggest that interaural difference cues, which are robust along the horizontal axis but minimal in the median plane, are not necessary for neural correlates of the PE to be manifested. Finally, single-neuron responses did not demonstrate a correlate of build-up of suppression, a phenomenon whereby echo suppression accumulates with ongoing stimulation. This finding adds credibility to theories about the PE that argue for a "higher order" component of the PE.

Lack of effect of methylmercury exposure from birth to adulthood on information processing speed in the monkey.

Although it is established that developmental methylmercury exposure produces severe motor and sensory impairment, the effect on cognitive function is less clear. To explore this issue, monkeys with robust methylmercury-induced deficits in visual, auditory, and somatosensory function were tested on a series of tasks assessing central processing speed, which is highly correlated with intelligence in humans. Five monkeys (Macaca fascicularis) were dosed from birth to 7 years of age with 50 micrograms/kg/day of mercury as methylmercuric chloride. Blood mercury levels were stable at 0.8-1.1 micrograms/g until cessation of dosing. When they were 20 years old, these monkeys and four age- and rearing-matched controls were tested on a series of simple and complex reaction time tasks. The monkey sat in a primate chair with a stainless steel bar centered at waist height. Four push buttons equidistant from the steel bar were mounted on a vertical Plexiglas panel in front of the monkey. The monkey was required to make contact with the bar, then release the bar and push the appropriate button in response to a change in stimulus conditions. For the first task (simple reaction time), the monkey was required to respond on a button when it changed from unlit to red. The monkey then performed a sequence of complex reaction time tasks: two-button, four-button, and several tasks of increasing complexity using four buttons and multiple colors. For each task, the latency to release the bar after the stimulus change (central processing speed) and to move the hand from the bar to the button (motor speed) were determined. Lastly, the monkey was required to make the quickest possible motor response on the simple reaction time task. There were no differences between groups on any aspect of the experiment. These data provide further evidence for absence of cognitive impairment in monkeys exposed developmentally to methylmercury.

Order and duration of stimuli are important determinants of reactivation

Prior cuing treatments intended to alleviate the forgetting of a conditioned avexsion-to an odor were tested with 18-day-old rats. Previous experiments had shown that when such pups were conditioned with the use of a CS−/CS+ procedure, pretest presentation of the CS− or US, but not the CS+, alleviated the forgetting otherwise seen after a 3-h retention interval. In Experiment 1, it was determined that the forgetting was not alleviated if the GS− was either preceded or followed by presentation of the CS+, despite the fact that the CS−/CS+ ordering mimicked that of original conditioning. Experiment 2 was an examination of the balance of extinction and reactivation effects caused by presenting the CS+ for varying durations following the 3-h retention interval. The forgetting over this interval was alleviated if the CS+ was presented for 5 or 15 sec, but not 30 sec. With an increase in duration of exposure from 15 to 30 sec, the consequences of the CS+ as a prior cuing treatment apparently shifted from reactivation to extinction. Experiment 3 was a test of the interaction between the consequences of different lengths of CS+ exposure and the effectiveness of adding CS− to the CS+ as a reactivation treatment. The varied effectiveness of reactivation treatments is discussed interms of a change in stimulus conditions from training to reactivation.

Apparent motion perception: the contribution of the binocular and monocular systems. An improved test based on motion aftereffects.

Research concerning the perception of apparent motion is not easy to conduct: it is hard to obtain quantitative results that can be easily interpreted. A solution to this problem is the use of motion aftereffects (MAEs). Adapting subjects to a specific type of motion leads to apparent motion in the opposite direction when the stimulus is removed. However, subjects are aware of the change in stimulus conditions. A new dynamic test stimulus is proposed in order to avoid artefacts introduced by the awareness of the conditions by the subject. A model, derived from earlier observations, is described which includes contributions from monocular and binocular systems. Results from an experiment in which the dynamic test stimulus was used show that they do not necessarily reproduce the results obtained with a static test stimulus. Central monocular systems are added to the model to account for this discrepancy. The 'pooling hypothesis', which states that the MAE is a weighted mean of the processes involved, permits the estimation of the weights of the individual subsystems. The results of the experiments are explained in terms of this hypothesis by the new model.

The Changing Face of Visual Persistence

In three experiments, the effect of target luminance on estimates of visual persistence was determined on a popular successive-field task. Even though the experiments differed from each other only in terms of minor changes in stimulus conditions, very different effects were obtained across the three experiments. The different findings were attributed to the often overlooked roles of masking and target degradation on tasks of persistence. Implications for the numerous contradictory findings in the persistence literature are discussed, and the current popularity of the successive-field task is questioned.

Effects of light and dark environments on macaque and human fixational eye movements

Eye position of two macaques and two humans was recorded while they detected the unpredictable dimming of a fixation spot in a dark or a light environment. Fixational saccades often had complex waveforms that resulted from clustering of two or more saccadic displacements with no intervening drift periods. In the dark, all subjects had low frequencies of saccade clusters (0.15-0.61/sec). Three of the subjects increased the frequency of saccade clusters and decreased the magnitude of the displacements when the task was performed in the normally lighted laboratory. The higher saccade frequencies in the light did not automatically result in greater dispersion of eye position. One of the humans, who had the lowest saccade frequency, was relatively unaffected by the stimulus conditions. The change in stimulus conditions had a more pronounced effect on the fixational eye movements of the macaques than the humans. In the dark, the macaques made saccades mostly down and nasal, but in the light the saccadic displacements occurred over a wider range of angular directions. Mean eye position was higher in the dark than in the light. The humans altered the direction of their saccadic displacements very little and did not change their mean eye position when they switched from a dark to a lighted environment. The influence of a lighted environment is interpreted as an interaction between foveolar and peripheral retinal inputs. The results suggest that fixational saccades may have more than one role, perhaps including stimulation of pathways originating in the peripheral retina. These peripheral field inputs have a stronger effect on the fixational control system of macaques than of humans.

Effects of chlorpromazine on fixed-ratio responding: modification by fixed-interval discriminative stimuli.

Effects of chlorpromazine (1 to 100 mg/kg) were assessed on two pigeons' responding under various modifications of a multiple schedule of food delivery. During a fixed-interval component, the first response after 5 min produced food; during the subsequent, fixed-ratio component, the 30th response produced food. Modifications of the schedule entailed changes in stimulus conditions imposed during the fixed-ratio component that did not systematically alter characteristics of performance under non-drug conditions. In the first phase of the experiment, distinctive visual stimuli were correlated with each schedule component (conventional multiple schedule); chlorpromazine produced small decreases in fixed-ratio responding (20% at 30 mg/kg). When each response during the fixed-ratio component produced the stimulus correlated with the fixed-interval schedule (fixed-interval discriminative stimulus) for 1.2 s, effects of chlorpromazine were not different from those under the conventional multiple schedule. Chlorpromazine produced greater decreases in fixed-ratio responding (55% at 30 mg/kg) when either the first response of each fixed ratio changed the stimulus correlated with the fixed-ratio schedule to the fixed-interval discriminative stimulus for the remainder of the fixed-ratio component, or when the fixed-interval discriminative stimulus was presented independently of responding according to a matched temporal sequence. When the fixed-interval discriminative stimulus was present continuously during the fixed-ratio component (mixed schedule), chlorpromazine produced even more substantial decreases in fixed-ratio responding (greater than 80% at 30 mg/kg). Effects of chlorpromazine on fixed-interval responding were also modified by the schedules of fixed-interval discriminative stimulus presentation. The effects of chlorpromazine were a joint function of the stimuli prevailing during the multiple schedule and the degree to which responding influenced these stimuli.

Interactions between Stimulus-Response Compatibility and Task Variables: Unexpected Effects

The nature of stimulus-response compatibility (SRC) effects related to left-right finger position within the hand were examined in two experiments requiring a centrally-located unimanual choice response. Experiment 1 Involved a letter recognition task with stimull presented at either a small (3.3 degrees) or large (13.3 degrees) visual angle. Effects consistent with finger position spatial compatibility were observed when stimull occured at the small visual angle, but not for the large visual angle. Experiment 2 examined the generalizability of these effects in a same-different letter matching task. The results indicate that spatial compatibility effects related to finger position can effect performance of more cognitive tasks, even when stimulus postion is irrelevant to determining the correct response. However, the effects vary with changes in stimulus conditions and task demands. There is a need for additional research examining the robustness of different types of SRC effects across tasks and across conditions varying stimulus and/or response eccentricity.

Control of myoelectrical responses through reinforcement.

A classic experiment by Hefferline, Keenan, and Harford (1959) showed that small thumb-twitches, imperceptible to the subject, can be controlled by the consequences of terminating and/or postponing aversive noise. These findings were further investigated in three experiments reported here. Experiment 1 replicated the original study. Experiment 2 was a control study in which stimulus changes were presented as in Experiment 1, but independently of the responses. Under these conditions the response rate varied over a large range with no systematic relation to experimental events. The increments in response rate reported by Hefferline et al. were within the present range of variation, suggesting that conditioning in the earlier study may have reflected a consistency in the direction of change rather than an increase in rate beyond the baseline range. In the present experiment, however, the rate increase was absolute. In Experiment 3, analog rather than binary changes in stimulus conditions were used as reinforcement. Under these conditions, the rates of subjects whose responses were conditioned fell from 78% (in the previous experiment) to 31%.

Infant Behavioral State and Speech Sound Discrimination

In order to investigate the interaction between infant state and speech sound discrimination, records of state were obtained from infants participating in 3 speech sound discrimination experiments which employed the high amplitude sucking procedure. A total of 94 individual records were rated for state by 2 independent scorers. When treated as an independent variable, state interacted with responsivity to sound change as measured by sucking rate increases. Infants in the more alert states demonstrated significantly higher rates of sucking following sound change. Treating state as a dependent variable revealed that state was not significantly affected by a change in stimulus conditions.

Modification of a learned vomiting ritual by change in stimulus conditions and self-controlled response prevention

A case of nightly bedtime vomiting of 16-yr duration in a normal adult was treated by instructing the subject in response prevention, rearranging stimulus conditions and substituting competing cognitions for the subject's thoughts about the condition of her stomach. Once the subject could refrain from vomiting, previously avoided foods were introduced in graduated amounts. The subject spontaneously resumed going to restaurants and accepting social engagements related to food. An avoidance paradigm is discussed as the main maintaining variable.

Effects of Imagery Instructions When the Context is Changed

In a test of the hypothesis that the superiority of paired-associate learning brought about by Imagery instructions would be diminished by a change in stimulus conditions from practice to test, 80 women subjects were run in a factorial study with the factors, instructions (either image or associate), test conditions (practice and test in same or different rooms), and test modality (memory drum or audio tape). Instructions to Image yielded a significantly greater number of correct responses as a main effect. Instructions × test conditions yielded a significant effect, with a reduced superiority of image over associate instructions when practice and test took place in different rooms.

Variability in somatosensory cortical neuron discharge: effects on capacity to signal different stimulus conditions using a mean rate code

1. The present study is based on the demonstration (8, 9) that the relationship between mean interval (MI) and standard deviation (SD) for stimulus-driven activity recorded from SI neurons is well fitted by the linear equation SD = a X MI + b and on the observations that the values of the slope (a) and y intercept (b) parameters of this relationship are independent of stimulus conditions and may vary widely from one neuron to the next (8). 2. A criterion for the discriminability of two different mean firing rates requiring that the mean intervals of their respective interspike interval (ISI) distributions be separated by a fixed interval (expressed in SD units) is developed and, on the basis of this criterion, a graphical display of the capacity of a neuron with a known SD-MI relationship to reflect a change in stimulus conditions with a change in mean firing rate is derived. Using this graphical approach, it is shown that the parameters of the SD-MI relationship for a single neuron determine a range of firing frequencies, within which that neuron exhibits the greatest capacity to signal differences in stimulus conditions using a frequency code. 3. The discrimination criterion is modified to incorporate the changes in the symmetry of the ISI distribution observed to accompany changes in mean firing rate. It is shown that, although the observed symmetry changes do influence the capacity of a cortical neuron to signal a change in stimulus conditions with a change in mean firing rate, they do not alter the range of firing rates (determined by the parameters of the SD-MI relationship) within which the capacity for discrimination is maximal. 4. The maximal number of firing levels that can be distinguished by a somatosensory cortical neuron (using the same discrimination criterion described above) discharging within a specified range of mean frequencies also is demonstrated to depend on the parameters of the linear equation which relates SD to MI. 5. Two approaches based on the t test for differences between two means are developed in an attempt to ascertain the minimum separation of the mean intervals of the ISI distributions necessary for two different mean firing rates to be discriminated with 80% certainty.

Discriminability and the contrafreeloading phenomenon.

According to previous reports of the "contrafreeloading phenomenon," animals will work for a reward, and sometimes work quite hard, in the presence of the same reward available freely. With rats as the subjects two experiments are presented which suggest that the contrafreeloading data are explainable with a basic learning principle, discriminability and its accompanying response decrement. For some animals the change in stimulus conditions with introduction of free water was made more highly discriminable by a change in earned reinforcement conditions. The other animals remained on the same earned reinforcement conditions under which all the animals had been trained. The results demonstrated that the discriminability between the conditions of working and freeloading is a most important factor contributing to the continued responding in the presence of free rewards.