Effects of response selection on the task repetition benefit in task switching

A task switch typically leads to worse performance than a repetition does. This shift cost can be reduced with sufficient task preparation time, but a residual cost usually remains. We propose that a large part of this residual cost is caused by an activation bias produced by response selection processes in the preceding trial. In our experiments, we manipulated response selection requirements using a go/no-go methodology. The residual shift cost disappeared after no-go trials, suggesting that response selection is crucial to establish an activation bias for the current category-response rules and that this bias persists into the next trial. A comparison with a go-only group confirmed this analysis by revealing no differences in preparatory strategy due to the inclusion of no-go trials. In addition, no-go trials had no significant effects on subsequent trials in a single-task experiment, suggesting that no-go trials are not coded as a task different from go trials and that there is no inhibition of the prepared task in a no-go trial. We thus conclude that a persisting activation bias of response rules plays a major role in task switching.     

Disruption of temporally organized behavior by morphine

Four pigeons pecked keys in two different procedures commonly used in the study of timing, or temporal discrimination. Sessions consisted of 40 trials. During half of the trials, two keys were presented for 50 s. Left-key pecks were reinforced according to a variable-interval 67.86-s schedule during the first 25 s of the trial, and right-key pecks were not reinforced. During the second 25 s of the trial, right-key pecks were reinforced according to the same schedule, and left-key pecks were not reinforced. In the other half of the 40-trial session, the center key was presented. The majority of these trials arranged fixed-interval 2.5-s schedules. Occasionally a probe, or peak-interval, trial was presented. These trials were 100 s in duration and terminated without reinforcement. These two procedures were used to examine the effects of morphine on indexes of timing and on patterns of responding. Morphine altered behavior in a race-dependent manner in both procedures. Low baseline (saline) response rates were increased following morphine administration, and high baseline rates were either unaffected or decreased slightly. Rate-dependent effects appeared as leftward shifts in the timing index for two-key trials and decreases in the index of curvature for fixed-interval trials. Despite large changes in response rates, no consistent shift of the peak time was observed during peak-interval trials. These results are discussed primarily in terms of rate dependency; that is, rates of responding following drug administration tend to be determined in large part by rates of responding under baseline conditions.     

The influence of reminder trials on contextual interference effects

Two experiments investigated the proposition of the elaboration explanation for contextual interference that more than one task is present in working memory when multiple tasks are practiced in a random schedule but that only one task is present in working memory when multiple tasks are practiced in a blocked schedule. Three motor tasks were performed as fast as possible in either a random or blocked practice schedule. At the end of practice, a reminder trial for each task was either given or not given. Acquisition performance was slower for the random practice conditions than for the blocked practice conditions. Retention performance was faster for the random practice conditions than for the blocked practice condition that did not receive a reminder trial for each task. Importantly, performance differences were not found between the random practice conditions and the blocked practice condition that did receive a reminder trial for each task. A blocked practice condition with a beneficial acquisition and reminder task order pairing performed faster during both acquisition and retention than a comparable random practice condition. Reminder trials can facilitate detailing of task characteristics, and their effectiveness is determined by the elapsed time and number of intervening tasks during acquisition and retention.     

The Influence of Reminder Trials on Contextual Interference Effects

Two experiments investigated the proposition of the elaboration explanation for contextual interference that more than one task is present in working memory when multiple tasks are practiced in a random schedule but that only one task is present in working memory when multiple tasks are practiced in a blocked schedule. Three motor tasks were performed as fast as possible in either a random or blocked practice schedule. At the end of practice, a reminder trial for each task was either given or not given. Acquisition performance was slower for the random practice conditions than for the blocked practice conditions. Retention performance was faster for the random practice conditions than for the blocked practice condition that did not receive a reminder trial for each task. Importantly, performance differences were not found between the random practice conditions and the blocked practice condition that did receive a reminder trial for each task. A blocked practice condition with a beneficial acquisition and reminder task order pairing performed faster during both acquisition and retention than a comparable random practice condition. Reminder trials can facilitate detailing of task characteristics, and their effectiveness is determined by the elapsed time and number of intervening tasks during acquisition and retention.     

A role for set in the control of automatic spatial response activation

Spatial stimulus-response (S-R) compatibility effects are widely assumed to reflect the automatic activation of a spatial response by the spatial attributes of a stimulus. The experiments reported here investigate the role of the participant's set in enabling or interacting with this putatively automatic spatial response activation. Participants performed a color discrimination task (Experiment 1) or a localization task (Experiment 2). In each experiment, two different S-R mappings were used and a task-cue indicated the appropriate mapping on each trial. S-R compatibility and the time between the task-cue and target were manipulated, and compatibility effects were assessed as a function of (a) the time between the task-cue and the stimulus, and (b) whether the S-R mapping repeated or switched on consecutive trials. Critically, whether response mappings repeated or switched on consecutive trials determined the relation between compatibility effects and the time between task-cue and stimulus. These results are discussed in terms of an interaction between automatic spatial response activation and the participant's set.     

Building tasks from verbal instructions: An EEG study on practice trial exposure and task structure complexity during novel sequences of behavior

Configuring the mind to perform a novel task is an effortful process and one that is related to differences in general intelligence. Previous research has suggested that when participants are given instructions for a future task, representations of the rules contained in the instructions can influence subsequent behavior, even when the rules are not necessary to perform the upcoming task. One hypothesis for the continued activation of rule representations suggests that the practice trials participants perform before the experimental trials may instantiate the unnecessary task rules into participants’ mental model of the task (i.e., the task space). To test this hypothesis, EEGs were recorded as participants (N = 66) completed a multirule task designed to contrast the effects of increasing task structure complexity and practice trial exposure. The results showed that, as was predicted, performance is significantly poorer when more task rules are specified in the task instructions. Practice trials with the extra rule did not affect task performance, indicating that an unacted verbal instruction is sufficient to incorporate the rule into participants’ mental model of the task. The EEG results showed that instruction complexity was linked to a phasic increase in frontal theta synchronization but reduced posterior alpha and beta desynchronization. These changes in synchronization occurred during a time period of low intertrial phase coherence and suggest that participants were “checking the task rules” amidst a trial. This transient neural activity may reflect compensatory mechanisms for dealing with increased mind-wandering that is more likely to occur in complex tasks.     

The role of knowledge of results frequency in learning through observation

The authors examined whether reduced knowledge of results (KR) frequency during observation of a model's performance enhances learning. As they viewed a timing task, observers (n = 54) received KR about the model's performance on each trial (100% KR) or on 1 out of 3 trials (33% KR). Controls (n = 18) received only physical practice; they did not take part in the observation session. The authors also wanted to dissociate the guidance effect of KR during physical practice from the guidance role played by the representation acquired during observation. Therefore, following the observation phase, participants physically performed the task with either the same or a different KR frequency than that experienced during observation. The effects of observation and physical practice on learning were assessed in delayed retention tests. The beneficial effect of reduced KR frequency during observation continued for the following physical practice phases. Possible explanations as to why KR influences observational learning are discussed.     

Effect of the length of the runs of repetitions on the simple RT-ISI relationship

In a simple RT task the temporal organization of the preparatory processes during a given trial depends upon the time characteristics of the total experimental situation as well as upon the information gathered during one or more previous trials. The present experiment was run in order to determine whether or not these long and short term effects operate independently or interact. The effects of the preceding ISI durations on the simple RT for an ISI 1 (1.5 s) or an ISI 2 (3.0 s) are analysed in 3 experimental conditions differing in the maximum number of successive repetitions (2, 3 or 7) of trials with the same ISI. The results show that the distribution of the preparatory activity during a given trial depends firstly on the number of successive ISIs of the same duration preceding this trial, and secondly on the maximum number of repetitions. An explanation of the subjects' strategy based upon “cost of preparation” is proposed.     

Parenting programmes for parents of children and young people with behavioural difficulties

Children and young people exhibiting behavioural difficulties present a major challenge not only to parents but also to education and health professionals and to society as a whole. In this paper, I shall address some key issues regarding these parenting programmes, based particularly on a programme of research over 13 years in the Centre for Educational Development, Appraisal and Research at the University of Warwick. This has comprised large‐scale studies across all areas of England, both programmes targeted at parents whose children are presenting or at risk of developing behavioural difficulties: the Parenting Early Intervention Pathfinder and Parenting Early Intervention Programme; and universal programmes aimed at all parents, as a positive contribution to behavioural development across the population: the CANparent trial. All were funded by the Department for Education plus the continuation of the CANparent trial was funded by the Department of Health. In addition, I consider studies that have built on this research to examine the use of parenting programmes with parents of children and young people with special educational needs; and also the effectiveness of programmes during sustained implementation, beyond formal trials and similar research initiatives, that is, as day‐to‐day practice. I show that well‐constructed parenting programmes that are acceptable to parents are effective, that these positive effects on parents can remain over time, and also that the positive effects found in well‐organised trials can be maintained when programmes are delivered by community services as part of their normal practice.     

Young People's Experiences of Participation in Clinical Trials: Reasons for Taking Part

Given the lack of knowledge about safety and efficacy of many treatments for children, pediatric clinical trials are important, but recruitment for pediatric research is difficult. Little is known about children's perspective on participating in trials. The purpose of this study was to understand the experiences and motivations of young people who took part in clinical trials. This is a qualitative interview study of 25 young people aged 10–23 who were invited to take part in clinical trials. Interviews were audio or video recorded and analyzed using framework analysis. Young peoples' motivations were both personal benefit and helping others. Both incentives appeared to be more complex than expected. We introduce the terms “network of exchange” and “intergenerational solidarity” to describe these motivations. To improve recruitment, professionals should be more open about research opportunities, provide better information, and give young people feedback after the trial has ended.     

Interference and negative priming from ignored distractors: The role of selection difficulty

The relation between distractor interference and negative priming from identical distractors was examined in two experiments. Subjects responded to a target letter, which was indicated by an adjacent bar marker, and attempted to ignore a distracting letter. Onprime trials, distracting letters were either compatible or incompatible with the target, allowing for a measure of interference. On subsequentprobe trials, previously ignored distractors were sometimes presented as targets, allowing for a measure of negative priming. Reducing the spatial separation between targets and distractors on the prime trial increased the magnitude of interferenceand negative priming, but these effects appeared to be independent of each other (Experiment 1). In Experiment 2, the prime target location was precued on some trials, but not on others. Precuing attenuated the magnitude of interference, but not that of negative priming effects. This pattern indicates that measures of negative priming and measures of distractor interference on the immediately preceding trial are independent. The results are discussed in terms of a selective inhibition model of selective attention.     

Motor skill acquisition and retention as a function of average feedback, summary feedback, and performance variability

Summary feedback involves withholding feedback from subjects until the last trial in a block is completed, and then presenting feedback about each trial. A variation of this method, called average feedback (Young & Schmidt, 1992), presents subjects with only the mean of the trial block. We investigated whether these methods have similar effects on acquisition and retention of a simple motor skill. Five groups of subjects (n = 16 per group) performed 60 acquisition trials of an aiming task involving both spatial and temporal accuracy. We presented average and summary feedback based on either 5-trial blocks or 15-trial blocks and compared these schedules with every-trial feedback. During acquisition, all groups improved with practice, with a slight tendency for the every-trial condition to have less absolute error than the longer summary and average conditions. Analysis of delayed no-feedback retention tests, however, revealed a strong advantage for the 5-trial summary and average conditions compared with the every-trial condition. In addition, we found that for long blocks of acquisition trials without augmented feedback, the performance variability of those trials was associated with retention performance. Results are discussed in terms of how these different manipulations may make feedback less useful during acquisition, but foster the use of certain information processing activities that enhance overall learning.     

Further Tests of Schmidt’s Schema Theory

The present study investigated the generalizability of Schmidt’s (1975) schema theory to an open-skill (Poulton, 1957) situation. Subjects attempted to time a preferred-hand button press so that it was coincident with the lighting of the last of a series of runway lights whose apparent velocity was 4023 mm/sec. Prior to five trials of performance on the criterion task, subjects received 40 trials in which they either (a) watched (low response requirements) or (b) responded with the nonpreferred hand (high response requirements) to a stimulus moving at (a) a constant (2235, 3129, 4917, or 5812 mm/sec) velocity (low stimulus variability) or (b) different velocities (high stimulus variability) from trial to trial. Subjects receiving high stimulus variability and high response requirements during training had significantly lower absolute error on the criterion task than did those in the other conditions. The results were discussed in terms of the type of practice which facilitates development of a schema rule for coincident-timing situations.     

Test-potentiated learning: three independent replications,a disconfirmed hypothesis,and an unexpected boundary condition

Arnold and McDermott [(2013). Test-potentiated learning: Distinguishing between direct and indirect effects of testing. Journal of Experimental Psychology: Learning, Memory, and Cognition, 39, 940–945] isolated the indirect effects of testing and concluded that encoding is enhanced to a greater extent following more versus fewer practice tests, referred to as test-potentiated learning. The current research provided further evidence for test-potentiated learning and evaluated the covert retrieval hypothesis as an alternative explanation for the observed effect. Learners initially studied foreign language word pairs and then completed either one or five practice tests before restudy occurred. Results of greatest interest concern performance on test trials following restudy for items that were not correctly recalled on the test trials that preceded restudy. Results replicate Arnold and McDermott (2013) by demonstrating that more versus fewer tests potentiate learning when trial time is limited. Results also provide strong evidence against the covert retrieval hypothesis concerning why the effect occurs (i.e., it does not reflect differential covert retrieval during pre-restudy trials). In addition, outcomes indicate that the magnitude of the test-potentiated learning effect decreases as trial length increases, revealing an unexpected boundary condition to test-potentiated learning.     

Further tests of Schmidt's schema theory: development of a schema rule for a coincident timing task

The present study investigated the generalizability of Schmidt's (1975) schema theory to an open-skill (Poulton, 1957) situation. Subjects attempted to time a preferred-hand button press so that it was coincident with the lighting of the last of a series of run way lights whose apparent velocity was 4023 mm/sec. Prior to five trials of performance on the criterion task, subjects received 40 trials in which they either (a) watched (low response requirements) or (b) responded with the nonpreferred hand (high response requirements) to a stimulus moving at (a) a constant (2235, 3129, 4917, or 5812 mm/sec) velocity (low stimulus variability) or (b) different velocities (high stimulus variability) from trial to trial. Subjects receiving high stimulus variability and high response requirements during training had significantly lower absolute error on the criterion task than did those in the other conditions. The results were discussed in terms of the type of practice which facilitates development of a schema rule for coincident-timing situations.     

INTERTRIAL INTERVAL DURATION AND LEARNING IN AUTISTIC CHILDREN

This study investigated the influence of intertrial interval duration on the performance of autistic children during teaching situations. The children were taught under the same conditions existing in their regular programs, except that the length of time between trials was systematically manipulated. With both multiple baseline and repeated reversal designs, two lengths of intertrial interval were employed: short intervals with the S^D for any given trial presented approximately one second following the reinforcer for the previous trial versus long intervals with the S^D presented four or more seconds following the reinforcer for the previous trial. The results showed that: (1) the short intertrial intervals always produced higher levels of correct responding than the long intervals; and (2) there were improving trends in performance and rapid acquisition with the short intertrial intervals, in contrast to minimal or no change with the long intervals. The results are discussed in terms of utilizing information about child and task characteristics in terms of selecting optimal intervals. The data suggest that manipulations made between trials have a large influence on autistic children's learning.     

The Effect of Remoteness on Intertrial Correlations in Pursuit Rotor Performance

120 male university students were tested on a Koerth pursuit rotor. One group of 60 Ss was tested on each of 6 days spaced throughout a 3-wk. period. Another group of 60 Ss performed the same task in an identical manner for test-retest days only, with the retest day following by 3 wk. One group had a large amount of practice while the other did not within a comparable time period. Each practice session consisted of 60 15-sec. trials. The effects of both practice and layoff on intertrial correlations separated by increasing remoteness was investigated. The findings indicated, as others have found, that correlations decrease in size as remoteness increases. Adjacent trial correlations were found to increase as practice increased.     

Is there "feedback" during visual imagery? Evidence from a specificity of practice paradigm.

The specificity of practice hypothesis predicts the development of a sensorimotor representation specific to the afferent feedback available during skill acquisition (Proteau, 1992; Proteau, Marteniuk, Girouard, & Dugas, 1987). In the present investigation, we used the specificity of practice hypothesis to test whether skill acquisition through visual imagery would lead to the development of a sensory-specific movement representation similar to one resulting from actual practice. To accomplish this objective, participants practiced walking a 12-m linear path in one of three practice conditions, full-vision (FV), no-vision (NV), or visual imagery (VI), for either 10 or 100 trials. Knowledge of spatial and/or temporal results (KR) was provided to participants following each trial during this phase. Following acquisition, participants completed 10 NV trials without KR. An analysis of root-mean-squared-error (RMSE) indicated NV participants were more accurate than both FV and VI participants in the transfer condition. We believe the equivalence in transfer RMSE between FV and VI suggests that there are similarities between the movement representations attained by FV and VI practice.     

Mixing location-irrelevant and location-relevant trials: influence of stimulus mode on spatial compatibility effects

The performance advantage for spatially compatible mappings of physical locations to keypress responses, relative to incompatible mappings, is eliminated when stimulus color, rather than location, is relevant on half of the trials. In Experiment 1, we compared the effects of mixing for different stimulus modes (physical locations, arrow directions, and location words) to determine whether this elimination of the stimulus-response compatibility (SRC) effect would generalize to other stimulus modes. The SRC effect was unaffected when the location information was conveyed by arrows and was amplified when the location information was conveyed by words. In Experiment 2, we used vocal left-right responses instead of keypresses, and the SRC effects for all three stimulus modes were enhanced by mixing. In both experiments, for all stimulus modes, mixing reduced or reversed correspondence effects for trials on which the location information was irrelevant when the mapping for those trials on which it was relevant was incompatible. These findings suggest that when trial types are mixed, direct activation of the corresponding response, regardless of mapping, does not occur for physical locations mapped to keypresses. However, such activation does occur when stimuli or responses are verbal, apparently because performance is mediated in part by activation of a verbal name code for the stimulus.