Effects of effort on response rate

Pigeons were trained to peck for food reinforcement, and the minimum effective force for a peck was varied. In a single-key situation, the response rate was unaffected up to a certain force value, beyond which increments caused a proportional decrement in response rate. Transient enhancement and suppression effects were observed following a change in the force requirement. A change from a high force requirement to a low force requirement resulted in a temporary enhancement of response rate above the stable performance level, whereas a change from a low to a high requirement produced a temporary suppression of the rate below the stable rate. In a two-key situation, the response rate on a key with a given force remained unaffected by the force requirement on the other key. When the rate of response was plotted against the required force, the resultant function was remarkably similar to that obtained from the single-key experiment. When the rates of reinforcement on the two keys differed, the decrement in response rate produced by an increase in the force requirement was proportionally greater on the key with the lower rate of reinforcement.     

Concurrent performances: synthesizing rate constancies by manipulating contingencies for a single response

An earlier experiment scheduled variable-interval reinforcement for pigeons' pecks on one key, and variable-interval reinforcement alternating with extinction, in a multiple schedule, for pecks on a second key. During the second key's extinction component, first-key pecking was relatively slow and continuous, rarely interrupted by second-key pecking; during the variable-interval component, first-key pecking was frequently interrupted by second-key pecking. When changeover delays operated, so that reinforced pecks on one key could not follow closely upon changeovers from the other key, rapid first-key pecking between interruptions compensated sufficiently for the time lost in second-key pecking that the overall rate of first-key pecking remained roughly constant across the alternating multiple-schedule components. The present experiments duplicated, on a single key, the temporal pattern of first-key pecking generated in the earlier experiments: components of continuous key availability were alternated with components of interrupted key availability. Approximately constant overall rates of responding were observed with a single-key equivalent of a changeover delay scheduled after interruptions and with manipulations of the on-off durations of the interruption cycle. Rate constancies in the original concurrent situation presumably depended on analogous contingencies that operated upon the concurrent responses, rather than on any constant “reserve” of responses.     

Relationship between rate of preparation for, and processing of, an event requiring a choice response

It is known that alcohol increases the time taken to identify signals and to make responses to them, but it is not known whether it also slows the rate of preparation for such events. These two performance parameters are not necessarily related, as age affects the former but not the latter. Twenty subjects participated in a 4-choice reaction time experiment in which they received no alcohol (NA) in the first session and either no alcohol (10 subjects) or 0.8 ml alcohol (A) per kg body weight (10 subjects) in the second session. In each session there were 300 practice trials, followed by 400 experimental trials at each one of five Response-Stimulus Intervals (RSI: 50, 100, 200, 400, and 800 msec). There was a significant effect of alcohol such that the reduction in response time from the first to the second session was 39 msec larger for the NA/NA group than for the NA/A group. Response time decreased significantly with increasing RSI, but there was no interaction between the effect of alcohol and RSI. Thus, alcohol slows the processing of an event requiring a choice response; however, like age and individual differences, but unlike practice, alcohol has no effect on the rate of preparation for that event. In addition, an analysis of what happened before and after an error revealed that practice and increasing RSI produce real improvements in performance rather than shifts in the tradeoff between speed and accuracy, whereas alcohol produces a real impairment. It is concluded that the relationship between the rate of preparation for, and processing of, a stimulus is not simple, as one factor (practice) influences both rates, whereas other factors (alcohol, individual differences, and age) influence the rate of processing only.     

Effects of antecedent order and semantic context on Chinese pronoun resolution

Three reading time experiments were conducted in order to examine the relative contributions of order of antecedents and semantic context to the resolution of temporarily ambiguous Chinese pronouns. These pronouns were ambiguous because each of them was preceded by two antecedents, both of which were likely candidates for coreference. The identity of the pronoun was revealed by subsequent disambiguating information that constrained the pronoun to one particular interpretation. Experiment 1 showed that reading of the disambiguating phrase was slower when the phrase confined the pronoun to the second rather than to the first antecedent. Experiment 2 produced the same effect of antecedent order (first vs. second antecedent) regardless of whether the target antecedent was an action-performing or an action-receiving entity. In Experiment 3, the order effect was eliminated by a biasing modifier inserted immediately before the pronoun. These results indicate that in a semantically neutral environment, the first-appearing antecedent is the preferred candidate for coreferencing the ambiguous Chinese pronoun. The interaction between order of antecedents and semantic context (in the form of preposed biasing modifiers) suggests that the initial comprehension of Chinese pronouns depends as much on contextual as on structural factors.     

Effects of variations in local reinforcement rate on local response rate in variable interval schedules

Rats trained to lever press for sucrose were exposed to variable-interval schedules in which (i) the probability of reinforcement in each unit of time was a constant, (ii) the probability was high in the first ten seconds after reinforcement and low thereafter, (iii) the probability was low for ten seconds and high thereafter, (iv) the probability increased with time since reinforcement, or (v) the probability was initially zero and then increased with time since reinforcement. All schedules generated similar overall reinforcement rates. A peak in local response rate occurred several seconds after reinforcement under those schedules where reinforcement rate at this time was moderate or high ([i], [ii], and [iv]). Later in the inter-reinforcement interval, local response rate was roughly constant under those schedules with a constant local reinforcement rate ([i], [ii], and [iii]), but increased steadily when local reinforcement rate increased with time since reinforcement ([iv] and [v]). Postreinforcement pauses occurred on all schedules, but were much longer when local reinforcement rate was very low in the ten seconds after reinforcement ([iii]). The interresponse time distribution was highly correlated with the distribution of reinforced interresponse times, and the distribution of postreinforcement pauses was highly correlated with the distribution of reinforced postreinforcement pauses on some schedules. However, there was no direct evidence that these correlations resulted from selective reinforcement of classes of interresponse times and pauses.     

Effects of repeated acquisitions and extinctions on response rate and pattern

The procedure developed by R. A. Rescorla (2002) was used to study the effects of repeated acquisitions and extinctions of head entry responses into a food cup by rats. In each of 4 20-session phases, food was delivered at the end of particular 30-s auditory and visual stimuli, but not at the end of different 30-s auditory and visual stimuli. Based on response rates to individual stimuli and compound stimuli, the increase in response rate in acquisition occurred more rapidly than the decrease in extinction. Acquisition, but not extinction, occurred faster after successive transitions between acquisition and extinction. Temporal gradients of responding developed during acquisition and remained during extinction. Conclusions based on mean response rate, temporal gradients, and transfer tests were consistent.     

Effects of the timing of postevent information on preschoolers' memories of an event

Few researchers have investigated whether the timing of postevent information affects the accuracy of children's reports of events they have experienced. In this study, four‐year‐olds dressed up in costumes and had their photographs taken. An unfamiliar adult spoke to the children about the event either a day (immediate condition) or a month (delayed condition) later, providing both accurate and misleading information about the staged event. When questioned five weeks after the event, children in a control group who had not received the review were more inaccurate answering focused questions than children who had been reminded of the event. A review a while after the event but shortly before the interview increased the amount of details recalled and this was not at the expense of accuracy. Misinformation was seldom reported spontaneously, although children in all groups acquiesced to leading questions in line with the misleading suggestions. Copyright © 1999 John Wiley & Sons, Ltd.     

Effects of thinning the rate at which the alternative behavior is reinforced on resurgence of an extinguished instrumental response

Three experiments with rats examined the effects of thinning the rate of reinforcement for the alternative behavior in the resurgence paradigm. In all experiments, pressing one lever (L1) was first reinforced and then extinguished while pressing a second alternative lever (L2) was then reinforced. When L2 responding was then extinguished, L1 responses "resurged." Resurgence was always observed when L2 was reinforced on an unchanging reinforcement schedule during Phase 2. However, other rats received systematic decreases in the rate of L2 reinforcement before extinction of L2 began. Such a "thinning" procedure was predicted to reduce final resurgence by associating L1 extinction with longer and longer periods without a reinforcer. The procedure did reduce the resurgence effect observed when L2 was put on extinction (Experiment 3). However, in each experiment, thinned groups also returned to L1 responding, and continued to make L1 responses, while the reinforcement schedule for L2 was being thinned. Fine-grained analysis of behavior in time suggested that this early resurgence was not due to adventitious reinforcement of L1, occasion setting of L1 by reinforcer presentation, or the entrainment of L1 as a schedule-induced interim behavior. The results are overall consistent with the hypothesis that resurgence is a renewal effect in which extinguished L1 responding recovers when the context provided by the L2 reinforcement schedule is changed. Challenges for this view are also discussed.     

Effects of event rate and display time on sustained attention in hyperactive,normal, and control children

Two experiments were conducted to determine whether hyperactive boys have a unique deficit in sustained attention. Groups with DSM-III diagnoses of attention deficit disorder (ADDH), conduct disorder (CD), ADDH+CD, and learning disorder were compared with normal controls on the Continuous Performance Task. In Experiment 1, stimulus presentation rate (stimulus onset asynchrony, SOA) and display time were varied to manipulate attentional demand, and speed and accuracy of performance were measured. The ADDH group was uniquely affected, with less accurate performance at the fastest and slowest SOA. To distinguish the effects of time on task and SOA, the duration of each SOA condition was held constant in Experiment 2. The poorer performance of the ADDH group at the fastest SOA was no longer evident. This finding indicates that the deficit of sustained attention in boys who have ADDH is associated with a greater susceptibility to refractory effects, which is influenced by practice.This research was supported by the Ontario Mental Health and Ruth Schwartz Foundations through a graduate fellowship awarded to P. Chee and a research grant to R. Schachar, G. Logan, and R. Wachsmuth. Dr. Schachar was also supported by the Canadian Psychiatric Research Foundation. This article is based, in part, on a doctoral dissertation submitted by the first author to the Ontario Institute for Studies in Education. The authors thank Dr. John Lovering and the staff of the Departments of Psychiatry and Psychology, The Hospital for Sick Children, for their cooperation in the conduct of this study. This paper was prepared with the assistance of the Medical Publications Department, The Hospital for Sick Children, Toronto.     

Modification of the rat's acoustic startle response by antecedent visual stimulation.

Male hooded and albino rats were exposed to a light flash followed at various temporal intervals by a startle-eliciting 117 db. (re 20 muN/m2) burst of white noise. The visual stimulus engendered startle response inhibition (maximally when the lead time was 64-250 msec) as well as startle response latency reduction (maximally when the lead time was 2-8 msec). The temporal functions for the effects of visual stimuli paralleled those previously reported for startle modification by acoustic events. Further study revealed that, given optimal lead times, inhibition is produced reliably by weaker visual stimuli (3 X 10-6 cd-sec/cm2) than latency reduction (3 X 10-4 cd-sec/cm2). This differential sensitivity to visual stimuli is also analogous to previously reported findings for events in the acoustic environment. It reveals that the neural mechanisms that mediate latency reduction and inhibition can be engaged by either acoustic or visual stimulation.     

Effects of event structure on retrospective duration judgments

Two experiments examined whether varying degrees of event coherence influence the remembering of an event’s actual duration. Relying on musical compositions (Experiment 1) or filmed narratives (Experiment 2) as experimental stimuli, the underlying hierarchy of information within events (i.e., melodic intervals or story elements) was either attentionally highlighted or obscured by placing a varying number of accents (i.e., prolonged notes or commercial breaks) at locations that either coincided or conflicted with grammatical phrase boundaries. When subjects were unexpectedly asked to judge the actual duration of events, through a reproduction (Experiment 1) or verbal estimation (Experiment 2) task, duration estimates became more accurate and less variable when the pattern of accentuation increasingly outlined the events’ nested relationships. Conversely, when the events’ organization was increasingly obscured through accentuation, time judgments not only became less accurate and more variable, but were consistently overestimated. These findings support a theoretical framework emphasizing the effects of event structure on attending and remembering activities.     

Effects of manipulating valence and arousal components of mood on specificity of autobiographical memory

An important cognitive deficit in clinical depression is the inability to be specific in recalling personal memories, a phenomenon coined "overgeneral memory" by Williams and Broadbent. Although there is general consensus that overgeneral memory is not state-dependent, most of the evidence originates from studies of this effect in clinical populations. The two components of mood, valence and arousal, were manipulated to examine their influence on memory specificity in a nonclinical sample of university undergraduate students. In Exp. 1, a Velten procedure was used to induce elated, depressed, or neutral mood states. No difference was found in autobiographical memory specificity among the three groups. In Exp. 2, high and low arousal states were induced through physical exercise. A low arousal state resulted in an increased proportion of overgeneral memories, suggesting that this memory phenomenon may be influenced by the arousal component of mood.     

Effects of an audio cueing system on the rate of teacher praise

The effects of automated cueing on teacher praise rate was investigated in one special, one fourth-, and one seventh-grade classroom. After establishing baseline praise rates in each of the three classrooms, two methods for increasing teacher praise rate were introduced according to a multiple-baseline design. During the first phase, two teachers were instructed to count and graph their praise rate during each session. All teachers received auditory cues to prompt praising during another phase. In all cases, introduction of cues markedly increased teacher praise rates, but self-recording was relatively ineffective. An analysis of teacher-praise distributions showed that cues closely controlled teacher praise for two of the three teachers.     

The response order effect: People believe the first person who remembers an event

When groups of people remember an event, the order in which they discuss their memories is important. In three experiments, a response order effect was shown in which participants believed the first speaker to be more accurate and more confident than a subsequent speaker. Further, participants were more likely to report as their own memory what the first speaker reported than what a subsequent speaker reported. The experiments showed that the response order effect was not due to intrinsic characteristics of what the first speaker said. Even when participants chose the response order themselves and the speakers’ dialogue was counterbalanced, participants still believed that the first speaker was more accurate and confident than a subsequent speaker. Because in most situations the person who introduces a particular topic into a discussion is more accurate, people may assume that this is true, even when the response order is random.     

Several antecedent strategies in reduction of an environmentally destructive behavior.

The effects of response-specific prompts, prompts identifying long-term and short-term consequences, a combination of long-term and short-term consequences, and a combination of short-term consequences and response-specific prompts on the reduction of environmentally destructive lawn-walking were investigated. The response-specific prompt alone was effective, and its effectiveness was enhanced by the identification of short-term and long-term consequences; however, the mere identification of short-term and long-term consequences alone was not effective.     

Effects of manipulating incentive visibility during the baiting phase of delayed-response problems

Rhesus monkeys were given 960 delayed response (DR) problems. The incentive was either visible or not visible during the baiting phase of each problem, and a 0-, 5-, 10-, or 20-sec intraproblem delay was imposed. Performance was substantially better when the incentive could be seen during the baiting phase. When the incentive was visible during baiting, at all stages of training performance decreased as a function of increased chance levels after short delays, and the rate of improvement with training was comparable after each of the four intraproblem delays. When the incentive was not visible during the baiting phase, an inverse relationship between performance and delay duration became evident only during the later stages of training. On the initial problems performance was at chance levels, and although improvement with training was evident, the rate of this improvement was inversely related to delay duration. The findings were interpreted in terms of Fletcher's orienting response analysis of DR performance.     

Effects of implied action speed on estimation of event duration

Two experiments investigated the effect of manipulating the implied speed of an individual's actions on estimation of event duration. Experiment 1 requested duration estimates from eyewitnesses to a staged event. Three groups of subjects participated, and each was provided with different postevent information, which varied the implied speed of the individual that acted out the event. Results indicated that subjects who were led to believe the actor engaged in fast actions (e.g. running) generated significantly shorter duration estimates than those led to believe the speed of the actor was slow (e.g. the actor walked). Experiment 2 manipulated implied action speed by varying the commands given by a robber during a bank robbery. The marked sound track contained phrases such as ‘hurry up’, ‘come on’, ‘now!’ which imply that the bank tellers, to whom the commands were directed, had a slow action speed. The unmarked sound track contained the same number of words as the marked tape, but they did not emphasize action speed. Both versions of the video had the same actual duration. Results indicated that subjects shown the marked video gave significantly longer duration estimates, than those shown the unmarked video. The results are discussed in terms of the reconstruction of event duration, and implications for assessing the accuracy of eyewitness testimony.