Mental planning and the Tower of London task

The Tower of London (TOL) task has been used extensively as a test of planning ability in neuropsychological patients and normal populations. Participants are asked to preplan mentally a sequence of moves to match a start set of discs to a goal, and then to execute the moves one by one. The mental preplanning stage has been identified as critical to efficient performance. The current experiments examined whether manipulations of mental preplanning influence performance on the TOL. In Experiment 1, the effect of different planning instructions was examined. Those told to make full mental plans spent considerably longer in planning than participants given no specific planning instructions, yet there was no effect of instruction condition on the efficiency of executing plans. Experiment 2 investigated whether people were able to plan mentally, by looking at their ability to identify intermediate states of an optimum mental plan. Results indicated that most individuals could make accurate preplans up to two subgoals ahead, but not three. However, making an efficient preplan did not result in better subsequent execution of moves to solve the TOL trial. It is concluded that people can make effective mental plans for a limited number of moves. However, on the TOL task, mental preplanning does not offer benefits in terms of quicker performance, or more accurate solution. The nature of planning in the TOL task is therefore questioned.     

Learned helplessness in chess players: The importance of task similarity and the role of skill

Summary The effects of noncontingency between subjects' responses and outcomes were examined with respect to treatment-and-posttest similarity and skill in the task. The experimental design consisted of three groups. The first group had to solve chess problems with objective solutions and received veridical feedback; each member of the second group faced problems with no objective solutions, and received the same feedback as the member of the first group he was yoked with, but without any control on it; the control group received a waiting task. It was found at the end of the experiment that the group with unsolvable problems was more depressed than the two other groups. The mid-strength players were the most sensitive to the manipulation, and the weakest players showed little effect of learned helplessness. It was also found that the effects were proportional to the degree of similarity between the treatment and the posttest. The results limit the domain of applicability of the learned-helplessness model.     

A complete database of international chess players and chess performance ratings for varied longitudinal studies

Chess is an oft-used study domain in psychology and artificial intelligence because it is well defined, its performance rating systems allow easy identification of experts and their development, and chess playing is a complex intellectual task. However, usable computerized chess data have been very limited. The present article has two aims. The first is to highlight the methodological value of chess data and how researchers can use them to address questions in quite different areas. The second is to present a computerized database of all international chess players and official performance ratings beginning from the inaugural 1970 international rating list. The database has millions of records and gives complete longitudinal official performance data for over 60,000 players from 1970 to the present. Like a time series of population censuses, these data can be used for many different research and teaching purposes. Three quite different studies, conducted by the author using the database, are described.     

The role of memory in the Tower of London task

The Tower of London (TOL) task is widely used as a neuropsychological test of planning. Relatively little is known of the cognitive components of the task, and in particular the role of memory in performance. The current studies on normal adults looked at the role of verbal and spatial working memory in the TOL. The effects of verbal and visuospatial dual-task manipulations on TOL performance were examined in an experiment with 36 participants. Both verbal and visuospatial executive secondary tasks caused poorer performance on the TOL; however, concurrent articulatory suppression enhanced performance. The results suggest that executive and spatial components are important in the task, and raise questions about the role of preplanning in the TOL.     

Deconstructing the tower: Parameters and predictors of problem difficulty on the Tower of London task

The Tower of London (TOL) task has been widely used in both clinical and research realms. In the current study, 104 healthy participants attempted all possible moderate- to high-difficulty TOL problems in order to determine: (1) optimal measures of problem solving performance, (2) problem characteristics, other than the minimum moves necessary to solve the problem, that determine participants’ difficulty in solving problems successfully, quickly, and efficiently, and (3) effects of increased task experience on which problem characteristics determine problem difficulty. A factor analysis of six performance measures found that, regardless of task experience, problem difficulty could be captured well either by a single factor corresponding to general quality of solution or possibly by three subordinate factors corresponding to solution efficiency, solution speed, and initial planning speed. Regression analyses predicting these performance factors revealed that in addition to a problem’s minimum moves three problem parameters were critical in determining the problem difficulty: goal position hierarchy, start position hierarchy, and number of solution paths available. The relative contributions of each of the characteristics strongly depended on which performance factor defined performance. We conclude that TOL problem performance is multifaceted, and that classifying problem difficulty using only the minimum moves necessary to solve the problem is inadequate.     

Age,working memory,and the Tower of London task

The current study explores the role of three components of working memory in age differences in an executive task, the Tower of London (TOL). The TOL task is sensitive to frontal lobe damage, and is widely used to measure planning ability. Dual tasks were used to test the involvement of the phonological loop (articulatory suppression), visuospatial buffer (pattern tapping), and central executive (random generation) in age effects on the TOL. Older adults showed greater reliance than young on domain-specific verbal and spatial memory components in performing the TOL. In terms of executive function, qualitatively different interference patterns were seen in young and old participants. However, the validity of using random generation tasks to assess executive function in older populations can be questioned. For older participants, performing the TOL loads all components of working memory, whereas for the younger participants the TOL more specifically loads executive functioning.     

A comparison of the risk‐taking behaviors of prisoners and non‐prisoners

Do prisoners and non‐prisoners differ in their risk‐taking behavior and the domains where they take risks? Surprisingly little psychological research has addressed these questions, despite the well‐established paradigms and extensive literature on risk taking among non‐prison populations. To fill this gap, we used the Domain‐Specific Risk‐Taking Scale to compare 75 male prisoners' and 75 male non‐prisoners' risk‐taking behavior, risk perception, and risk benefit in five domains (ethical, financial, health, recreational, and social). Our results show that prisoners and non‐prisoners did not differ in their risk‐taking behavior in the ethical, financial, recreational, or social domains. In the health domain, however, prisoners exhibited significantly higher risk‐taking tendencies. With regard to risk perception, prisoners perceived activities as significantly more risky than non‐prisoners, aside from the financial domain where non‐prisoners reported significantly higher risk perception. In all five domains, prisoners perceived risk‐taking activities as offering fewer benefits compared to the non‐prisoner sample. Our results also indicate that risk‐taking activities are better predicted by the expected benefits than by risk perception for both prisoners and non‐prisoners in the recreational, financial, and ethical domains. However, for prisoners, risk taking in the social domain increased with level of perceived benefit. In the health domain, prisoners' risk taking decreased with increasing level of perceived risk, whereas for non‐prisoners, perceived benefits, but not risk perception, predicted risk taking. Copyright © 2010 John Wiley & Sons, Ltd.     

Interruption of the Tower of London task: support for a goal-activation approach

Unexpected interruptions introduced during the execution phase of simple Tower of London problems incurred a time cost when the interrupted goal was retrieved, and this cost was exacerbated the longer the goal was suspended. Furthermore, time taken to retrieve goals was greater following a more complex interruption, indicating the processing limitations may be as important as time-based limitations in determining the ease of goal retrieval. Such findings cannot simply be attributed to task-switching costs and are evaluated in relation to current models of goal memory (E. M. Altmann & G. J. Trafton, 2002; J. R. Anderson & S. Douglass, 2001), which provide a useful basis for the investigation and interpretation of interruption effects.     

Deliberate practice predicts performance over time in adolescent chess players and drop‐outs: A linear mixed models analysis

In this study, the longitudinal relation between deliberate practice and performance in chess was examined using a linear mixed models analysis. The practice activities and performance ratings of young elite chess players, who were either in, or had dropped out of the Dutch national chess training, were analysed since they had started playing chess seriously. The results revealed that deliberate practice (i.e. serious chess study alone and serious chess play) strongly contributed to chess performance. The influence of deliberate practice was not only observable in current performance, but also over chess players' careers. Moreover, although the drop‐outs' chess ratings developed more slowly over time, both the persistent and drop‐out chess players benefited to the same extent from investments in deliberate practice. Finally, the effect of gender on chess performance proved to be much smaller than the effect of deliberate practice. This study provides longitudinal support for the monotonic benefits assumption of deliberate practice, by showing that over chess players' careers, deliberate practice has a significant effect on performance, and to the same extent for chess players of different ultimate performance levels. The results of this study are not in line with critique raised against the deliberate practice theory that the factors deliberate practice and talent could be confounded.     

A four‐disc version of the Tower of London for clinical use

Three studies are reported on the development of a four‐disc version of the Tower of London test of planning ability. The first (n = 138) involved the selection of items based on rational and empirical criteria to provide a short test of graded difficulty suitable for use with children and clinical populations. The second study (n = 480) checked the properties of the 10‐item test on a new sample and in addition examined the internal consistency and factor structure of the test. The third study (n = 61) examined the test – retest reliability of the test over a period of 1 month. The difficulty level of the test remained relatively stable from sample to sample and was sensitive to linear trend in performance from age 5 years up to 30 years. Total score did not reflect the action of a single underlying construct but rather appeared to index a number of factors. Scores were reasonably stable over the 1‐month period studied, at least for the children's sample employed. The four‐disc version is a promising method of assessing planning in children and adolescents in clinical situations.     

Performance of healthy, older adults on the Tower of London Revised: Associations with verbal and nonverbal abilities

Neuropsychological studies suggest a subclinical impairment in executive function that occurs with normal aging. This is the first study to examine the performance of healthy older adults on the Tower of London-Revised (TOL-R), as well as the relationship between TOL-R performance and verbal and nonverbal abilities. Performance of 63 older adult participants on the TOL-R and two WAIS-III subtests was compared to that of 35 young adult college students. Group comparisons indicated age differences in TOL-R performance; however, these were eliminated after adjusting for individual differences in Matrix Reasoning performance. In the older adult groups, multiple regression analyses demonstrated that Matrix Reasoning performance was a stronger predictor of TOL-R performance than was chronological age or years of education. These results suggest that performance on the TOL-R is a psychometrically sound executive function measure for older adults and that individual differences in fluid intelligence are more predictive of performance than chronological age.     

Deconstructing the Tower of London: Alternative moves and conflict resolution as predictors of task performance

Despite widespread use the cognitive demands of the five-disc Tower of London (TOL) are unknown. Research suggests that conflict moves (those that are essential to the solution but do not place a disc in its final position) are a key aspect of performance. These were examined in three studies via a verification paradigm, in which normal participants were asked to decide whether a demonstrated move was correct. Experiment 1 showed that individual move latencies increase with the number of intermediate moves until the disc is placed in its goal position (resolution). Post hoc tests suggested that the number of alternative moves and moves to resolve a disc were independent predictors of performance. Experiment 2 successfully manipulated these factors in an experimental design. Experiment 3 showed that they remain determinants of performance as familiarity increased. Overall, errors on the task were significantly correlated with spatial memory. The implications of these findings for the use of the TOLin cognitive psychology and as an assessment tool are discussed.     

Planning and Problem solving Using the Five disc Tower of London Task

This paper investigates the planning and problem-solving abilities of normal adult subjects using a complex version of Shallice's (1982, 1988) Tower of London (TOL) task. Subjects were required to plan a fluent solution to a range of 5-disc TOL puzzles and then execute their formulated plans as fast as possible. The number of errors and the times taken to prepare the most efficient solutions increased monotonically with the number of chunks of subgoal moves. A subgoal move is a move that is essential for the solution of the puzzle, but which does not place a disc into its goal position. A subgoal chunk is a consecutive series of subgoal moves that all transfer discs to and from the same pegs. Furthermore, preparation time was found to be sensitive to a manipulation that increased the number of competing alternative choices, at critical steps in move selection. When subjects planned their action sequences 'on-line', analyses of individual moves and individual move latencies suggested that planning TOL solutions was limited by the difficulty in evaluating and selecting one action (or one subgoal chunk) from the set of competing potential actions at each step in the course of problem solving.     

Visuo-spatial and verbal working memory in the five-disc Tower of London task: An individual differences approach

This paper reports a study of the roles of visuo-spatial and verbal working memory capacities in solving a planning task—the five-disc Tower of London (TOL) task. An individual differences approach was taken. Sixty adult participants were tested on 20 TOL tasks of varying difficulty. Total moves over the 20 TOL tasks was taken as a measure of performance. Participants were also assessed on measures of fluid intelligence (Raven's matrices), verbal short-term storage (Digit span), verbal working memory span (Silly Sentence span), visuo-spatial short-term storage (Visual Pattern span and Corsi Block span), visuo-spatial working memory (Corsi Distance Estimation), visuo-spatial processing speed (Manikin test), and verbal speed (Rehearsal speed). Exploratory factor analysis using an oblique rotation method revealed three factors which were interpreted as (1) a visuo-spatial working memory factor, (2) an age-speed factor, and (3) a verbal working memory factor. The visuo-spatial and verbal factors were only moderately correlated. Performance on the TOL task loaded on the visuo-spatial factor but did not load on the other factors. It is concluded that the predominant goal-selection strategy adopted in solving the TOL relies on visuo-spatial working memory capacity and particularly involves the active “inner scribe” spatial rehearsal mechanism. These correlational analyses confirm and extend results previously obtained by use of dual task methods, (Phillips, Wynn, Gilhooly, Della Sala, & Logie, 1999).     

Assessing planning ability with the Tower of London task: psychometric properties of a structurally balanced problem set

In clinical and experimental settings, planning ability is typically assessed using the Tower of London (ToL) or one of its variants. For enhancing the comparability across studies, a common ToL problem set was recently suggested comprising a collection of 4- to 7-move problems. Based on previous theoretical and empirical analyses of problem space and task structure, development of the problem set accounted particularly for the influence of structural problem parameters on the detection of individual differences in planning ability. To assess its adequacy as a clinical and research instrument, the present study evaluated the psychometric properties of the suggested problem set. Results showed a clear and nearly perfect linear increase of task difficulty across minimum moves. Given a broad range of item difficulty, high- and low-achieving subjects could be well discriminated. The test scores' split-half reliability (r = .72) and internal consistency (α = .69) were satisfactory. Taken together, the ToL problem set evaluated here proved to have good psychometric qualities and constitutes a conceptually sound basis for diagnostic and research purposes.     

Cognitive testing in non‐demented Turkish immigrants ‐ comparison of the RUDAS and the MMSE

Nielsen, T. R. Vogel, A., Gade, A. & Waldemar, G. (2012). Cognitive testing in healthy Turkish immigrants ‐ comparison of the RUDAS and the MMSE. Scandinavian Journal of Psychology 53, 455–460. Methods for culturally and linguistically appropriate cognitive testing of elderly minority populations are lacking in Europe. The aim of this study was to compare performance on the Rowland Universal Dementia Assessment Scale (RUDAS) and the Mini Mental State Examination (MMSE) in Turkish immigrants in Denmark and determine the impact of demographic and health‐related variables on test performance. A sample of non‐demented community‐dwelling Turkish immigrants was recruited from the greater Copenhagen area. All participants completed a structured interview regarding demographic, physical and mental health status, as well as measures of depression and acculturation, and cognitive testing with the RUDAS and the MMSE. A total of 76 non‐demented participants aged 50 or more were included in the study. The mean performance on the RUDAS and the MMSE was 26.8 (SD 2.4) and 23.7 (SD 4.3), respectively. In group comparisons, correlation analyses and regression analyses, level of schooling represented a more significant variable for RUDAS and MMSE performance than any other variable. However, the impact of schooling was considerably more pronounced on the MMSE and the test was not found to be a valid measure of general cognitive function in subjects with less than five years of schooling. Although not entirely free of educational bias, the RUDAS can be a valuable supplement to the MMSE for assessment of general cognitive function in Turkish minority populations.