An evaluation of time-sample measures of behavior

Continuous and time-sample measures of the in-seat behavior of a secretary were obtained. Measurement error, i.e., the extent to which the sample measures deviated from the continuous measure, was a function of the frequency of the sample measurements and the criterion used to score an example of the behavior. If the behavior had to be exhibited throughout the observational interval (whole-interval time sampling), there was a consistent underestimate of the continuous measure. If the behavior had to be exhibited only briefly within the observational interval (partial-interval time sampling), there was a consistent overestimate of the continuous measure. And, if the behavior had to be exhibited at the end of the observational interval (momentary time sampling), overestimations and underestimations of the continuous measure occurred about equally often. As expected, the more frequently the sample measures were made the closer was the agreement between the sample and continuous measures. Two conclusions concerning measurement error in interval time sampling were made. The first was that the error will be a function of the mean time per response. The second is that this error will not be consistent across experimental conditions.     

ON THE INABILITY OF INTERVAL TIME SAMPLING TO REFLECT FREQUENCY OF OCCURRENCE DATA1

Interval time sampling yields the result, percentage of intervals scored. It is rudimentary to note that this measure per se does not constitute a response dimension. It is a useful behavioral measure, therefore, only to the extent that it accurately reflects the nature and degree of the fundamental dimensions from which it is drawn i.e., frequency and duration. The correspondence between scored intervals and response duration is fairly well understood (Journal of Applied Behavior Analysis, 1975, 8 , 463–469; 1977, 10 , 325–332). This study determined the correspondence between scored intervals and response frequency. Eleven, 30-minute experimental sessions that differed along the variables of frequency of occurrence and time per response (the average length of a response per session) were computer simulated. In the first group of four sessions, the frequencies were 45, 100, 150, and 300; in these sessions, all responses ranged from one to three seconds. In the second group of four sessions, the frequencies were 31, 61, 101, and 152; in these sessions, all responses ranged from three to nine seconds. In the last group of three sessions, the frequencies were 25, 34, and 50; here, all responses ranged from nine to 27 seconds. The response distribution within the above ranges was rectangular, with each whole second represented once. The responses were selected by a random number generator, and on each trial every number in the distribution had an equal probability of occurrence. These provisions produced a linear pattern of responding. The time per response in the three groups of sessions were 2, 6, and 18 seconds. For all sessions, event recordings were made and analyzed. The analysis consisted of using partial interval time sampling to determine the percentage of intervals scored; this total was subdivided into intervals containing (1) single responses, (2) multiple responses, (3) continuing responses, and (4) response initiations or terminations. The analysis was performed when the length of the observation interval was 5, 10, 20, 30, 60, and 120 seconds. An additional session drawn from a study that contained real-life data was subjected to this same analysis. The most significant results were derived by finding the ratio of scored intervals containing single responses to the total intervals scored. If every scored interval contained a single response, this ratio would equal 1.0; if no scored interval contained a single response, the ratio would be 0.0. It can be seen that this ratio is an objective expression of the validity of interval time sampling as a measure of response frequency. Of 66 data points (11 sessions × six observation lengths per session), only five were equal to or greater than 0.80. These five points were all found in just two sessions (f = 45, 100). A validity index of less than 0.50 was observed in 49 of the 66 points. Also, the validity index increased, peaked, and then decreased within sessions as the length of the observation interval was increased. The results from the real-life session were in close agreement with those obtained from the simulations. The importance of these and previous findings lies in the demonstration that changes in scored intervals need not represent true behavior change. The data indicate that there are many combinations of behavioral frequency and duration where interval time sampling cannot produce valid measurement results.     

A COMPARISON OF INDIRECT MEASURES FOR LONG-DURATION BEHAVIORS1

A computer program was developed to simulate long-duration behavior. The program generated data by using two time-series models linked together by a covariance parameter. By varying the parameters of the program, the characteristics of the simulated behavior were altered, including the mean and variance of the durations of behavior, the mean and variance of the interresponse time, and the degree of relationship within and between durations of behavior and interresponse times. Four data-collection methods were applied to the simulated data: whole interval, partial interval, momentary time-sampling, and continuous measures. The accuracies of the first three recording measures were judged by comparing them to the continuous measure. The results indicated that only the momentary time-sampling approach yielded unbiased results. The degree of bias for the whole and partial interval measures was a function of the ratio of the interval recording length to the sum of the mean duration of behavior and the mean interresponse time. Unfortunately, it was concluded that researchers cannot estimate the magnitudes of these latter two parameters for most behaviors of interest and, consequently, are unable to choose an appropriate interval length. Therefore, it was recommended that the use of interval recording approaches be greatly restricted and that momentary time-sampling be substituted where possible.     

Quantifying false positives in simulated events using partial interval recording and momentary time sampling with dual‐criteria methods

The dual‐criteria (DC) and conservative dual‐criteria (CDC) methods allow clinicians and researchers to quantify the occurrence of false‐positive outcomes within single‐case experimental designs. The purpose of the current study was to use these DC and CDC methods to measure the incidence of false positives with simulated data collected via discontinuous interval methods (i.e., momentary time sampling, partial‐interval recording) as a function of data series length. We generated event data to create 316,800 unique simulated data series for analysis. In Experiment 1, we evaluated how changes in relevant parameters (i.e., interval sizes, event durations, IRT‐to‐event‐run ratios) produced false positives with momentary time sampling procedures. We also assessed the degree that the CDC method produced fewer false positives than the DC method with simulated interval data. In Experiment 2, we used similar procedures to quantify the occurrence of false positives with partial‐interval recording data. We successfully replicated outcomes from previous research in the current study, though such results only highlight the generality of the procedures relating to false positive (and not false negative) outcomes. That is, these results indicate MTS and PIR may adequately control for false positives, but our conclusions are limited by a lack of data on power.     

Detecting Changes in Simulated Events Using Partial‐Interval Recording and Momentary Time Sampling III: Evaluating Sensitivity as a Function of Session Length

In a series of two studies, we graphed simulated data representing continuous duration recording and continuous frequency recording into ABAB reversal designs depicting small, moderate, and large behavior changes during 10‐min, 30‐min, and 60‐min sessions. Data sets were re‐scored using partial‐interval recording and momentary time sampling with interval sizes set at 10 s, 20 s, 30 s, 1 min, and 2 min. In study 1, we visually inspected converted data for experimental control and compared the conclusion with those from the respective continuous duration recording or continuous frequency recording data to test for false negatives. In study 2, we evaluated the extent to which interval methods that were sensitive to changes in study 1 produced false positives. In part, the results show that momentary time sampling with interval sizes up to 30 s detected a wide range of changes in duration events and frequency events during lengthier observation periods. The practical implications of the findings are briefly discussed. Copyright © 2011 John Wiley & Sons, Ltd.     

Effects of decreasing intersession interval duration on graduated exposure treatment during simulated routine dental care

Reports suggest that individuals with developmental disabilities often engage in behavior during dental visits that precludes regular dental care. Graduated exposure therapies are an effective treatment for avoidant behavior in people with developmental delays, and some studies show that the duration of the intersession interval (ISI) can impact the effectiveness of graduated exposure treatments for typically developing individuals. The current study examined the effects of decreasing ISI on outcomes of a graduated exposure treatment during simulated routine dental care for 3 individuals diagnosed with autism. Treatment consisted of graduated exposure and extinction for disruptive behavior. Initially, sessions were conducted once per week. In subsequent conditions, treatment sessions were conducted 3‐5 times per week. A nonconcurrent multiple baseline across subjects design was used to demonstrate experimental control. Results suggest that decreasing ISI durations can produce improved treatment outcomes.     

Bouts of responding from variable-interval reinforcement of lever pressing by rats

Four rats obtained food pellets by lever pressing. A variable-interval reinforcement schedule assigned reinforcers on average every 2 min during one block of 20 sessions and on average every 8 min during another block. Also, at each variable-interval duration, a block of sessions was conducted with a schedule that imposed a variable-ratio 4 response requirement after each variable interval (i.e., a tandem variable-time variable-ratio 4 schedule). The total rate of lever pressing increased as a function of the rate of reinforcement and as a result of imposing the variable-ratio requirement. Analysis of log survivor plots of interresponse times indicated that lever pressing occurred in bouts that were separated by pauses. Increasing the rate of reinforcement increased total response rate by increasing the rate of initiating bouts and, less reliably, by lengthening bouts. Imposing the variable-ratio component increased response rate mainly by lengthening bouts. This pattern of results is similar to that reported previously with key poking as the response. Also, response rates within bouts were relatively insensitive to either variable.     

DETECTING CHANGES IN NON‐SIMULATED EVENTS USING PARTIAL INTERVAL RECORDING AND MOMENTARY TIME SAMPLING: EVALUATING FALSE POSITIVES,FALSE NEGATIVES,AND TRENDING

Several studies have evaluated false positives and false negatives produced with partial interval recording (PIR) and momentary time sampling (MTS) using simulated data. However, no study to date has evaluated false positives and negatives using a large sample of non‐simulated behaviors. In addition, few studies have evaluated whether interval methods of data collection alter trends that are evident in continuous records. We conducted three experiments to evaluate the extent to which various interval sizes of MTS and PIR produced false negatives (Experiment 1), false positives (Experiment 2), and trends that were inconsistent with the continuous records (Experiment 3). Collectively, the results show the following: (i) 10‐s PIR and 10‐s MTS produced few false negatives and few false positives (i.e., both were sensitive) to changes in duration events; (ii) 10‐s PIR produced very few false negatives, but an unexpected high percentage of false positives for frequency events; and (iii) each interval size of PIR and MTS produced a high percentage of changes in trending for duration events and frequency events. We briefly discuss the potential limitations and clinical implications of these findings. Copyright © 2012 John Wiley & Sons, Ltd.     

Interval recording for duration events: a re‐evaluation

In two experiments, events that were recorded using continuous duration recording (CDR) were rescored using 10‐s partial interval (PIR), 10‐s momentary time sampling (MTS) and 20‐s MTS. Results of Experiment 1 showed that data paths generated by each interval method produced conclusions about functional control that were similar to those based on CDR when using reversal designs; however, for multielement designs, 10‐s PIR was prone to showing differentiation between data paths that was not evident with CDR. Results of Experiment 2 showed that both 10‐s and 20‐s MTS yielded data paths on behavior–behavior relations (e.g., covarying responses) that were consistent with CDR whereas 10‐s PIR produced some behavior–behavior patterns that were not. In both experiments, 10‐s MTS generated data paths that were nearly identical to the respective CDR data paths. The implications of these findings for researchers and clinicians are briefly discussed. Copyright © 2007 John Wiley & Sons, Ltd.     

Methods of time sampling: A reappraisal of momentary time sampling and partial interval recording

We compared the accuracy of momentary time sampling (MTS) and partial interval recording (PIR) in estimating both absolute behavioral levels and relative change. A computer randomly generated runs of pseudobehavior varying in duration and rate and simulated MTS and PIR of each run. Results indicated that when estimating absolute behavioral levels, duration rather than rate should be used as the dependent measure, and MTS is more accurate than PIR. In contrast, PIR is the more sensitive method for detecting relative changes in behavioral levels, although, at high rates, PIR tends to underestimate the degree of change.     

A further examination of the lexical-processing stages hypothesized by the E-Z Reader model

Participants’ eye movements were monitored while they read sentences in which high- and low-frequency target words were presented normally (i.e., the normal condition) or with either reduced stimulus quality (i.e., the faint condition) or alternating lower- and uppercase letters (i.e., the case-alternated condition). Both the stimulus quality and case alternation manipulations interacted with word frequency for the gaze duration measure, such that the magnitude of word frequency effects was increased relative to the normal condition. However, stimulus quality (but not case alternation) interacted with word frequency for the early fixation time measures (i.e., first fixation, single fixation), whereas case alternation (but not stimulus quality) interacted with word frequency for the later fixation time measures (i.e., total time, go-past time). We interpret this pattern of results as evidence that stimulus quality influences an earlier stage of lexical processing than does case alternation, and we discuss the implications of our results for models of eye movement control during reading.     

Validation of continuous measures of peer social interaction with self- and teacher-reports of friendship and social engagement

ABSTRACT

The present study validates a new procedure that combines continuous measures of proximity (Ubisense) and vocalization (LENA) into measures of peer social interaction. The data were collected from 4 boys and 5 girls (ages 2–3 at the outset) on 8 separate days (3–4 hours per day) over the course of an academic year. Teacher reports of friendship were positively correlated with continuous measures of dyadic social interaction (i.e., the amount of time two children spent in proximity to one another, talking). Self-reports of reciprocated friendship were marginally correlated with continuous measures of dyadic social interaction, but only in the spring semester (when children were older and their reports of friendship more reliable). At the individual level, peer nominations of likeability, and teacher ratings of sociability and withdrawal were correlated with continuous measures of social interaction (i.e., the amount of time a child spent in proximity to other children, talking).     

The role of the response-reinforcer relation in delay-of-reinforcement effects

The role of the response-reinforcer relation in maintaining operant behavior under conditions of delayed reinforcement was investigated by using a two-operandum (i.e., two-key) procedure with pigeons. Responding on one key was reinforced under a tandem variable-interval differential-reinforcement-of-other-behavior (tandem VI DRO) schedule. The schedule defined a resetting unsignaled delay-of-reinforcement procedure in that a response was required when the interfood interval of the VI schedule lapsed, but further responding during the DRO component on either key reset the time interval. This ensured a fixed delay duration between any response and reinforcement. Responding on another key, physically identical to the first one except for spatial location, otherwise was without consequence. The location of the key correlated with the delay-of-reinforcement procedure varied between sessions according to a semirandom sequence. Differences in response rates between the two keys were greater, with proportionally higher rates on the key correlated with the delay-of-reinforcement procedure, the longer the delay-of-reinforcement procedure remained correlated with the same key. Differences in responding on the two keys also increased within individual sessions. These results suggest that the response-reinforcer relation is the primary determinant of responding when responding is acquired and maintained with delayed reinforcement.     

The reliability and validity of discrete and continuous measures of psychopathology: a quantitative review

In 2 meta-analyses involving 58 studies and 59,575 participants, we quantitatively summarized the relative reliability and validity of continuous (i.e., dimensional) and discrete (i.e., categorical) measures of psychopathology. Overall, results suggest an expected 15% increase in reliability and 37% increase in validity through adoption of a continuous over discrete measure of psychopathology alone. This increase occurs across all types of samples and forms of psychopathology, with little evidence for exceptions. For typical observed effect sizes, the increase in validity is sufficient to almost halve sample sizes necessary to achieve standard power levels. With important caveats, the current results, considered with previous research, provide sufficient empirical and theoretical basis to assume a priori that continuous measurement of psychopathology is more reliable and valid. Use of continuous measures in psychopathology assessment has widespread theoretical and practical benefits in research and clinical settings.     

A Review of: “Kennedy-Moore,E., & Lowenthal,M. S. (2011). Smart Parenting for Smart Kids: Nurturing Your Child's True Potential.”

Behavioral procedures aimed at decreasing disruptiveness through increasing self-evaluative skills and programming generalization in a class of disruptive retarded children were examined. Phases of the study included: (a) baseline; (b) systematic feedback; (c) a token economy; (d) matching of teacher's ratings by students; (e) four fading phases during which progressively fewer students were required to match the teacher; (f) self-evaluation during which each student received the amount of points self-allotted regardless of teacher's ratings; (g) doubling of point costs of back-up reinforcers ("Inflation"); (h) complete removal of back-up reinforcers ("Points Only"); and (i) return to baseline conditions. The class was observed 5 days per week dueing a morning experimental period and several times per week in the afternoon as a measure of generalization. Additional measures of generalization included days when the token program was not in effect ("Off Days") and when the class was taught by a substitute teacher. Behavior was recorded according to an interval sampling observational code. The results showed that systematic feedback was effective in significantly reducing disruptiveness with even greater reductions resulting from the token program and the subsequent matching and fading phases. Decreased levels of disruptiveness were maintained throughout self-evaluation and the phases which followed. Decreased levels of disruption also generalized to afternoon sessions, to days when the experimental procedures were not in effect, and to self-evaluate, the class initially matched the teacher's ratings with about 50% accuracy. This gradually increased to consistently above 90% during the latter phases. The study demonstrated that retarded children can learn to accurately observe and veridically evaluate their own behavior, and that this has beneficial effects in terms of decreased disruptiveness.     

Exploring the dynamics of design fluency in children with and without ADHD using artificial neural networks

The neuropsychology of attention deficit/hyperactivity disorder (ADHD) has been extensively studied, with a general focus on global performance measures of executive function. In this study, we compared how global (i.e., endpoint) versus process (i.e., dynamic) measures of performance may help characterize children with and without ADHD using a design fluency task as a case study. The secondary goal was to compare the sensitivity of standard versus connectionist statistical models to group differences in cognitive data. Thirty-four children diagnosed with ADHD and 37 children without ADHD aged 8–11 years old were tested on the Five-Point Test. The continuous process measure of performance, indexed as the number of produced designs at each consecutive 1 minute interval during 5 minutes, was analyzed against the discrete process measure, that is, the number of designs between first and last intervals and the standard global performance measure of total number of produced designs. Results show that the continuous process measure distinguished the two groups better than the two other measures. The detailed observation of production patterns revealed a decreasing linear trajectory in children without ADHD that contrasts with the flat, but fluctuating productivity pattern of children with ADHD. With regards to the second goal, results show that the connectionist and standard methods are equally sensitive to group differences for the three types of measures. This illustrates the utility of quantitative process measures together with the connectionist method in neuropsychological research and suggests great potential for a dynamical approach to cognition.     

Determinants of pigeons' waiting time: Effects of interreinforcement interval and food delay

Four pigeons performed on three types of schedules at short (i.e., 10, 30, or 60 s) interreinforcement intervals: (a) a delay-dependent schedule where interreinforcement interval was held constant (i.e., increases in waiting time decreased food delay), (b) an interreinforcement-interval-dependent schedule where food delay was held constant (i.e., increases in waiting time increased interreinforcement interval), and (c) a both-dependent schedule where increases in waiting time produced increases in interreinforcement interval but decreases in food delay. Waiting times were typically longer under the delay-dependent schedules than under the interreinforcement-interval-dependent schedules. Those under both-dependent schedules for 1 subject were intermediate between those under the other two schedule types, whereas for the other subjects waiting times under the both-dependent procedure were similar either to those under the delay-dependent schedule or to those under the interreinforcement-interval-dependent schedule, depending both on the subject and the interreinforcement interval. These results indicate that neither the interreinforcement interval nor food delay is the primary variable controlling waiting time, but rather that the two interact in a complex manner to determine waiting times.     

Step changes in the intertrial interval in the midsession reversal task: Predicting pigeons' performance with the learning-to-time model

Our goal was to assess the role of timing in pigeons' performance in the midsession reversal task. In discrete-trial sessions, pigeons learned to discriminate between 2 stimuli, S1 and S2. Choices of S1 were reinforced only in the first half of the session and choices of S2 were reinforced only in the second half. Typically, pigeons choose S2 before the contingency reverses (anticipatory errors) and S1 after (perseverative errors), suggesting that they time the interval from the beginning of the session to the contingency reversal. To test this hypothesis, we exposed pigeons to a midsession reversal task and, depending on the group, either increased or decreased the ITI duration. We then contrasted the pigeons' performance with the predictions of the Learning-to-Time (LeT) model: In both conditions, preference was expected to reverse at the same time as in the previous sessions. When the ITI was doubled, pigeons' preference reversal occurred at half the trial number but at the same time as in the previous sessions. When the ITI was halved, pigeons' preference reversal occurred at a later trial but at an earlier time than in the previous sessions. Hence, pigeons' performance was only partially consistent with the predictions of LeT, suggesting that besides timing, other sources of control, such as the outcome of previous trials, seem to influence choice.     

Temporal information affects the performance of numerosity discrimination: Behavioral evidence for a shared system for numerosity and temporal processing

In this study, we tested whether and how temporal information would affect the performance of numerosity discrimination in sequential events, in an attempt to make the relationship clear between temporal and numerosity processing. We manipulated the duration of event presentation (i.e., the stimulus duration) and the duration of the sequence (i.e., the total interval). We also employed three levels of standard event numbers (i.e., 5, 10, and 20) to test whether and how the effect would differ among event numbers. The results showed that temporal information affected the performance of numerosity discrimination; precision deteriorated when stimulus duration and the total interval were manipulated, and the number of events in the longer total interval were judged as less numerous than those in the shorter total interval across standard numbers. Accordingly, our results suggested the existence of a shared system between time and numerosity processing.     

Session duration and the VI response function: Within-session prospective and retrospective effects

Two experiments examined the effects of session duration on responding during simple variable-interval schedules. In Experiment 1, rats were exposed to a series of simple variable-interval schedules differing in both session duration (10 min or 30 min) and scheduled reinforcement rate (7.5 s, 15 s, 30 s, and 480 s). The functions relating response rate to reinforcement rate were predominantly monotonic for the short (10-min) sessions but were predominantly bitonic for the long (30-min) sessions, when data from the entire session were considered. Examination of responding within sessions suggested that differences in the whole-session data were produced by a combination of prospective processes (i.e., processes based on events scheduled to occur later in the session) and retrospective processes (i.e., processes based on events that had already occurred in the session). In Experiment 2, rats were exposed to a modified discrimination procedure in which pellet flavor (standard or banana) predicted session duration (10 min or 30 min). All rats came to respond faster during the short (10-min) sessions than during the first 10 min of the long sessions. As in Experiment 1, the results seemed to reflect the simultaneous operation of both prospective and retrospective processes. The results shed light on the recent controversy over the form of the variable-interval response function by identifying one variable (session duration) and two types of processes (prospective and retrospective) that influence responding on these schedules.