A comparison of token and tandem schedules of reinforcement on response patterns for adolescents with autism

Token schedules of reinforcement are ubiquitous in clinical settings, yet little research has thoroughly evaluated the effects of token schedules on responding in clinical settings. Basic research has shown token schedules of reinforcement produce lower response rates and larger pre‐ratio pauses compared to tandem schedules. The purpose of the current study was to determine whether the same effects are produced with adolescents with autism or related disorders. We examined response patterns under otherwise identical FR token and FR tandem schedules. Tokens suppressed responding for one participant only under high schedule values and for a second participant under common clinical schedule values; no difference in responding occurred between token and tandem schedules for two participants. These results support the systematic evaluation of token schedules of reinforcement in clinical settings. Additional applied research is needed on token schedules to further our understanding of the underlying mechanisms that contribute to the overall effectiveness of token economies.     

A Greek-Language Inventory of Fears: Psychometric Properties and Factor Structure of Self-Reports of Fears on the Hellenic Fear Survey Schedule

The structure of fearfulness and the psychometric properties of a Greek-language version of the Fear Survey Schedule were studied in a sample of normal Greek adults. Overall summary scores were higher for women than for men, had satisfactory temporal stability and internal consistency, and were useful in discriminating levels of phobic anxiety independent of levels of depression as assessed by a concurrent self-report measure. However, the temporal stabilities of responses for many items were inadequate for the reliable identification of levels of fear of specific events and objects. A factor analysis yielded five components that were conceptually similar to those obtained abroad. Subscales based on component items were psychometrically reliable. In comparison with American subjects, Greek subjects rated similar items as most fearful, but reported higher levels of fears of these items, reflecting either higher levels of fears, greater disclosure, or cultural differences in the meaning of fear ratings.     

PDP再认型实验程序与刺激来源的可鉴别性研究

提出应根据实验程序的不同,把加工分离模型（ＰＤＰ）进一步分为启动型和再认型两类。２个实验考察了刺激来源的可 鉴别性在ＰＤＰ的再认型实验程序中的作用,同时还考察了注意水平、刺激材料和加工水平等因素对词单１刺激项目再认成绩的影 响。结果发现：熟悉感和刺激来源的可鉴别性共同决定了被试在排除测验中的反应;汉字作刺激材料并不影响实验结果。     

Loneliness and Dread as Time Sense Disturbances

Our consciousness of time is created by our longing over duration for the care of a nurturing other. By means of a case study, it is shown here that the experience of abject loneliness is dependent upon a disturbed consciousness of time: unmet needs over the passage of time. Loneliness as such is the denial of the present moment—its possibilities and its demands. The loss of the present moment fosters a disturbed judgment of time: the sense that the present moment has stopped—is virtually endless, since the present moment has no future toward which to intend. This time disturbance diminishes the subject's capacity for agency.     

Synthesizing concurrent interval performances

Concurrent schedules may be viewed as consisting of two pairs of stay and switch schedules, each pair associated with one of the alternatives. A stay schedule arranges reinforcers for staying and responding at one alternative, whereas the associated switch schedule arranges reinforcers for switching to the other alternative. In standard concurrent schedules, the stay schedule at each alternative is equivalent to the switch schedule at the other alternative. MacDonall (1999) exposed rats to one pair of stay and switch variable-ratio schedules and varied the response requirements across conditions. Combining results from symmetric pairs produced composite performances that were described by the generalized matching law. This outcome was noteworthy because the data were obtained from performances at two alternatives with contingencies that were functionally unrelated to each other. This result suggests that concurrent performances may consist of two unrelated performances that alternate as behavior moves between alternatives. The purpose of the present experiment was to extend those results to interval schedules. Rats were exposed to pairs of random-interval schedules, and across conditions their mean intervals were varied. When data from appropriately paired conditions were combined, the composite performances were consistent with the generalized matching law. In addition, the results supported two models of concurrent performances that were based on local variables at an alternative (behavior, and stay and switch reinforcers): a modified version of the contingency discrimination model (Davison & Jenkins, 1985) and the local model (MacDonall, 1999).     

Oral drug self-administration in rhesus monkeys: interactions between drug amount and fixed-ratio size.

During daily 3-hr sessions, 5 rhesus monkeys drank drug solutions and water that were concurrently available. The drug solutions were: 1 milligram per milliliter (mg/mL) pentobarbital (2 monkeys), 1 mg/mL pentobarbital plus 0.5% ethanol (1 monkey), 1 mg/mL pentobarbital plus 1% ethanol (1 monkey), and 8% ethanol (1 monkey). The drug solution and water were available under identical two-component tandem fixed-ratio continuous-reinforcement N schedules. Two variables were manipulated: the size of the fixed-ratio component and the number of liquid deliveries (N) in the second component. Deliveries of the drug solution maintained higher rates of responding than did deliveries of the drug vehicle, water. The number of drug deliveries per session increased with increases in the number of deliveries per fixed ratio and decreased with increases in fixed-ratio size. Analysis of the results in terms of the proportion of deliveries to responses showed that the number of drug deliveries per session was directly related to the size of this quotient. Finally, when fixed-ratio size was repeatedly doubled, the following orderly relationship emerged: The greater the number of available drug deliveries per fixed ratio, the less was the percent decrease in the number of fixed ratios completed per session. It was concluded that increases in the number of liquid deliveries per fixed ratio resulted in increases in reinforcing efficacy.     

Homogeneous chains, heterogeneous chains, and delay of reinforcement

Three pigeons responded on two-component chain schedules in which the required response topography in the initial and terminal links was similar (a homogeneous chain) or dissimilar (a heterogeneous chain). Key-peck responding in the initial link under a variable-interval 60-second (VI 60) schedule produced a terminal link in which, in different conditions, either key pecking or foot treadling was reinforced according to a VI 60 schedule. Multiple VI 60 VI 60 schedules, in which the responses required in the chain schedules were maintained by primary reinforcement in the two components, preceded and followed each type of chain. These multiple schedules were used to ensure that both responses occurred reliably prior to introducing the chain schedule. Key-peck response rates in the initial link of the chain consistently were higher during the homogeneous chain than during the heterogeneous chain. These results illustrate that intervening events during a period separating an operant response from primary reinforcement influence that operant, independently of the delay between the response and reinforcement.     

A ROLE FOR NEGATIVE REINFORCEMENT OF RESPONSE OMISSION IN PUNISHMENT?

This experiment attempted to disentangle response-rate reductions controlled by the direct suppressive effects of a punisher from those due to negative reinforcement of response omission. Key-peck responding of pigeons was maintained by a conjoint variable-interval 3-min schedule of food presentation variable-interval 30-s schedule of response-dependent electric shock presentation. Omission of responses for 5, 10, or 30 s resulted in the possibility of canceling a scheduled shock. Response rates were a function of required pause duration, with lower rates occurring when longer periods of response omission were required for shock cancellation. These results show that, with several parameters of punishment held constant, response rates were controlled by the negative reinforcement contingency. Such a finding argues for renewed consideration of the role of negative reinforcement in punishment contingencies.     

Interaction of methadone, reinforcement history, and variable-interval performance.

In the present study, we examined how a reinforcement schedule history that generated high or low rates of responding influenced the effects of acute (Experiment 1) and chronic (Experiment 2) methadone administration. Initially, key-peck responses of pigeons were maintained under a variable-interval 90-s schedule of food presentation, and a methadone dose-response curve was determined with doses of 0.6, 1.2, and 2.4 mg/kg. The pigeons were then exposed, for at least 40 sessions, to either a fixed-ratio 50 schedule or a differential-reinforcement-of-low-rate 10-s schedule, or were given continued exposure to the variable-interval schedule. The methadone dose-response curve was redetermined after all pigeons again were responding under the variable-interval schedule. The effects of two different daily methadone doses (9.0 and 12.0 mg/kg/day) and withdrawal precipitated by naloxone also were assessed. Experience with a fixed-ratio or differential reinforcement of low rate schedule did not result in significantly different response rates under the variable-interval schedule and, in general, the acute effects of methadone did not have differential effects correlated with schedule history. However, for 2 of 4 subjects the rate-decreasing effects of methadone on rates of key pecking were greater following a history of low-rate responding, suggesting a possible interaction between schedule history and effects of methadone. Daily methadone administration under the variable-interval schedule revealed that pigeons with experience under the differential reinforcement of low rate schedule developed more rapid and complete tolerance to the rate-decreasing effects of methadone. Three of the 4 subjects in this group showed rate increases above drug-free baselines during chronic methadone dosing. Pigeons with a history of fixed-ratio responding also developed tolerance to the rate-decreasing effects of methadone but without the subsequent rate increases seen by subjects with low-rate histories. No subjects with variable-interval histories showed complete recovery of drug-free baselines, suggesting that interpolated training under other schedules may attenuate the rate-altering effects of chronically administered drugs. Naloxone (1.0 mg/kg), administered during the chronic methadone phase, resulted in greater disruption of responding by pigeons with a history of low-rate responding, as compared to subjects in the other two groups.(ABSTRACT TRUNCATED AT 400 WORDS)     

Preference for multiple versus mixed schedules of reinforcement

Five pigeons were trained in a concurrent-chain procedure. In the initial links, equal nonindependent variable-interval schedules were available concurrently on two keys. Completing the schedule on either key led to exclusive presentation of one of two further variable-interval schedules for a fixed period of time. During these terminal links, as many reinforcers as were scheduled could be obtained. If the response producing this terminal link occurred on one key, differential stimuli signaled which variable-interval schedule had been produced. If the response producing the terminal link occurred on the other key, no such differential stimuli were available. Once the fixed period of time elapsed, the initial links were reinstated. In Experiment 1, the period of time for which the terminal links were available was always 10 s and the absolute duration of the initial links was varied. Subjects preferred the alternative leading to the multiple schedule when the initial-link duration was short, but preferred the alternative leading to the mixed schedule when the initial-link durations were longer. In Experiment 2, both the initial-link duration and the duration of the terminal links were varied. The effect of initial-link duration was identical to that in Experiment 1 and there was no systematic effect of varying the terminal-link duration.