Parallel and identical test-retest reliability of the Tower of London test - Freiburg version.

OBJECTIVES: The Tower of London - Freiburg version (TOL-F) was developed in three parallel-test versions (A, B, and C) that only differ in their physical appearance by interchanged ball colors, but not in their cognitive demands. We addressed the question whether the test-retest reliability of an identical problem set differs from the parallel test-retest reliability of a structurally identical problem set with a marginally different physical appearance. METHODS: Reliabilities were assessed in two samples of young adults over a 1-week interval: In the parallel test-retest sample (n = 93; 49 female), half of the participants accomplished version A at the first session and version B at the second session, while the other half started with version B in the first session and continued with A in the second session. In the identical test-retest sample (n = 86; 48 female), half of the participants performed on version A in both the first and the second session, while the other half went through the same procedure with version B. RESULTS: For overall planning accuracy, intraclass correlation coefficients for absolute agreement were r = .501 for the parallel test-retest and r = .605 for the identical test-retest sample, with Pearson correlations of r = .559 and r = .708 respectively. Greatest lower bound estimates of reliability were adequate to high in the two samples (ranging between .765 and .854) confirming previous studies. CONCLUSIONS: Although the TOL-F revealed only moderate intraclass correlations for absolute agreement, it showed some of the highest psychometric indices compared to repeated assessments with other TOL tests.

Assessing Planning Ability Across the Adult Life Span in a Large Population-Representative Sample: Reliability Estimates and Normative Data for the Tower of London (TOL-F) Task.

OBJECTIVES: The Tower of London (TOL) test has probably become the most often used task to assess planning ability in clinical and experimental settings. Since its implementation, efforts were made to provide a task version with adequate psychometric properties, but extensive normative data are not publicly available until now. The computerized TOL-Freiburg Version (TOL-F) was developed based on theory-grounded task analyses, and its psychometric adequacy has been repeatedly demonstrated in several studies but often with small and selective samples. METHOD: In the present study, we now report reliability estimates and normative data for the TOL-F stratified for age, sex, and education from a large population-representative sample collected in the Gutenberg Health Study in Mainz, Germany (n=7703; 40-80 years). RESULTS: The present data confirm previously reported adequate indices of reliability (>.70) of the TOL-F. We also provide normative data for the TOL-F stratified for age (5-year intervals), sex, and education (low vs. high education). CONCLUSIONS: Together, its adequate reliability and the representative age-, sex-, and education-fair normative data render the computerized TOL-F a suitable diagnostic instrument to assess planning ability. (JINS, 2019, 25, 520-529).

Age differences in behavioral and neural correlates of proactive interference: Disentangling the role of overall working memory performance.

Reliable performance in working memory (WM) critically depends on the ability to resist proactive interference (PI) from previously relevant WM contents. Both WM performance and PI susceptibility are subject to cognitive decline at older adult age. However, the behavioral and neural processes underlying these co-evolving developmental changes and their potential interdependencies are not yet understood. Here, we investigated PI using a recent-probes WM paradigm and functional MRI in a cross-sectional sample of younger (n=18, 10 female, 23.4 ± 2.7 years) and older adults (n=18, 10 female, 70.2 ± 2.7 years). As expected, older adults showed lower WM performance and higher PI susceptibility than younger adults. Resolution of PI activated a mainly bilateral frontal network across all participants. Significant interactions with age indicated reduced neural activation in older adults for PI resolution. A second analysis in a selection of younger and older adults (n=12 each) with matched WM performance also revealed significant differences in PI between both age groups and - on a descriptive level - again a hypo-activation of the older adults' PI network. But the differential effect of age on the neural PI effects did not reach significance in this smaller sample most likely to the reduced statistical power. However, given the highly similar patterns in both the overall and the WM-matched samples, we propose that the hypo-activation of the PI network in the older adults may not be attributable to age-related differences in overall WM performance, hence suggesting that higher PI susceptibility in older adult age does not directly depend on their lower WM performance.

Training of resistance to proactive interference and working memory in older adults: a randomized double-blind study.

BACKGROUND: Working memory (WM) performance is often decreased in older adults. Despite the growing popularity of WM trainings, underlying mechanisms are still poorly understood. Resistance to proactive interference (PI) constitutes a candidate process that contributes to WM performance and might influence training or transfer effects. Here, we investigated whether PI resistance can be enhanced in older adults using a WM training with specifically increased PI-demands. Further, we investigated whether potential effects of such a training were stable and entailed any transfer on non-trained tasks. METHOD: Healthy old adults (N = 25, 68.8 ± 5.5 years) trained with a recent-probes and an n-back task daily for two weeks. Two different training regimens (high vs. low PI-amount in the tasks) were applied as between-participants manipulation, to which participants were randomly assigned. Near transfer tasks included interference tasks; far transfer tasks assessed fluid intelligence (gF) or speed. Immediate transfer was assessed directly after training; a follow-up measurement was conducted after two months. RESULTS: Both groups similarly improved in PI resistance in both training tasks. Thus, PI susceptibility was generally reduced in the two training groups and there was no difference between WM training with high versus low PI demands. Further, there was no differential near or far transfer on non-trained tasks, neither immediately after the training nor in the follow-up. CONCLUSION: PI-demands in WM training tasks do not seem critical for enhancing WM performance or PI resistance in older adults. Instead, improved resistance to PI appears to be an unspecific side-effect of a WM training.

fMRI characterization of visual working memory recognition.

Encoding and maintenance of information in visual working memory have been extensively studied, highlighting the crucial and capacity-limiting role of fronto-parietal regions. In contrast, the neural basis of recognition in visual working memory has remained largely unspecified. Cognitive models suggest that recognition relies on a matching process that compares sensory information with the mental representations held in memory. To characterize the neural basis of recognition we varied both the need for recognition and the degree of similarity between the probe item and the memory contents, while independently manipulating memory load to produce load-related fronto-parietal activations. fMRI revealed a fractionation of working memory functions across four distributed networks. First, fronto-parietal regions were activated independent of the need for recognition. Second, anterior parts of load-related parietal regions contributed to recognition but their activations were independent of the difficulty of matching in terms of sample-probe similarity. These results argue against a key role of the fronto-parietal attention network in recognition. Rather the third group of regions including bilateral temporo-parietal junction, posterior cingulate cortex and superior frontal sulcus reflected demands on matching both in terms of sample-probe-similarity and the number of items to be compared. Also, fourth, bilateral motor regions and right superior parietal cortex showed higher activation when matching provided clear evidence for a decision. Together, the segregation between the well-known fronto-parietal activations attributed to attentional operations in working memory from those regions involved in matching supports the theoretical view of separable attentional and mnemonic contributions to working memory. Yet, the close theoretical and empirical correspondence to perceptual decision making may call for an explicit consideration of decision making mechanisms in conceptions of working memory.

Differential impact of continuous theta-burst stimulation over left and right DLPFC on planning.

Most neuroimaging studies on planning report bilateral activations of the dorsolateral prefrontal cortex (dlPFC). Recently, these concurrent activations of left and right dlPFC have been shown to double dissociate with different cognitive demands imposed by the planning task: Higher demands on the extraction of task-relevant information led to stronger activation in left dlPFC, whereas higher demands on the integration of interdependent information into a coherent action sequence entailed stronger activation of right dlPFC. Here, we used continuous theta-burst stimulation (cTBS) to investigate the supposed causal structure-function mapping underlying this double dissociation. Two groups of healthy subjects (left-lateralized stimulation, n = 26; right-lateralized stimulation, n = 26) were tested within-subject on a variant of the Tower of London task following either real cTBS over dlPFC or sham stimulation over posterior parietal cortex. Results revealed that, irrespective of specific task demands, cTBS over left and right dlPFC was associated with a global decrease and increase, respectively, in initial planning times compared to sham stimulation. Moreover, no interaction between task demands and stimulation type (real vs. sham) and/or stimulation side (left vs. right hemisphere) were found. Together, against expectations from previous neuroimaging data, lateralized cTBS did not lead to planning-parameter specific changes in performance, but instead revealed a global asymmetric pattern of faster versus slower task processing after left versus right cTBS. This global asymmetry in the absence of any task-parameter specific impact of cTBS suggests that different levels of information processing may span colocalized, but independent axes of functional lateralization in the dlPFC.

Linking planning performance and gray matter density in mid-dorsolateral prefrontal cortex: moderating effects of age and sex.

Planning of behavior relies on the integrity of the mid-dorsolateral prefrontal cortex (mid-dlPFC). Yet, only indirect evidence exists on the association of protracted maturation of dlPFC and continuing gains in planning performance post adolescence. Here, gray matter density of mid-dlPFC in young, healthy adults (18-32 years) was regressed onto performance on the Tower of London planning task while accounting for moderating effects of age and sex on this interrelation. Multiple regression analysis revealed an association of planning performance and mid-dlPFC gray matter density that was especially strong in late adolescence and early twenties. As expected, for males better planning performance was linked to reduced gray matter density of mid-dlPFC, possibly due to maturational processes such as synaptic pruning. Most surprisingly, females showed an inverted, positive interrelation of planning performance and mid-dlPFC gray matter density, indicating that sexually dimorphic development of dlPFC continues during early adulthood. Age and sex are hence important moderators of the link between planning performance and gray matter density in mid-dlPFC. Consequently, the assessment of moderator effects in regression designs can significantly enhance understanding of brain-behavior relationships.

Dissociable stages of problem solving (II): first evidence for process-contingent temporal order of activation in dorsolateral prefrontal cortex.

In a companion study, eye-movement analyses in the Tower of London task (TOL) revealed independent indicators of functionally separable cognitive processes during problem solving, with processes of building up an internal representation of the problem preceding actual planning processes. These results imply that processes of internalization and planning should also be distinguishable in time and space with respect to concomitant brain activation patterns. To investigate this possibility, here we conducted analyses of fMRI data for left and right dorsolateral prefrontal cortex (dlPFC) during problem solving in the TOL task by accounting for the trial-by-trial variability of onsets and durations of the different cognitive processing stages. Comparisons between stimulus-locked and response-locked modeling approaches affirmed that activation in left dlPFC was elicited particularly during early processes of internalization, comprising the extraction of goal information and the generation of an internal problem representation, whereas activation in right dlPFC was predominantly attributable to later processes of mental transformations on this representation, that is planning proper. Thus, present data corroborate the proposal that often observed bilateral dlPFC activation patterns during complex cognitive tasks such as problem solving may reflect functionally and, to some extent, even temporally separable processes with opposing lateralizations.

Dissociable contributions of left and right dorsolateral prefrontal cortex in planning.

It is well established that the mid-dorsolateral prefrontal cortex (dlPFC) plays a critical role in planning. Neuroimaging studies have yielded predominantly bilateral dlPFC activations, but the existence and nature of functionally specific contributions of left and right dlPFC have remained elusive. In recent experiments, 2 independent parameters have been identified which substantially determine planning: 1) the degree of interdependence between consecutive steps (search depth) and 2) the degree to which the configuration of the goal state renders the order of single steps either clearly evident or ambiguous (goal hierarchy). Thus, search depth affects the actual mental generation and evaluation of action sequences, whereas goal hierarchy reflects the extraction of goal information from an encountered problem. Here, both parameters were independently manipulated in an event-related functional magnetic resonance imaging study using the Tower of London task. Results revealed a double dissociation as indicated by a significant crossover interaction of hemisphere and task parameter: in left dlPFC, activations were stronger for higher demands on goal hierarchy than on search depth, whereas the reversed result emerged in right dlPFC. In conclusion, often observed bilateral patterns of dlPFC activation in complex tasks may reflect the concomitant operation of specific cognitive processes that show opposing lateralizations.

Revising superior planning performance in chess players: the impact of time restriction and motivation aspects.

In a previous study (Unterrainer, Kaller, Halsband, & Rahm, 2006), chess players outperformed non-chess players in the Tower of London planning task but exhibited disproportionately longer processing times. This pattern of results raises the question of whether chess players' planning capabilities are superior or whether the results reflect differences in the speed-accuracy trade-off between the groups, possibly attributable to sports motivation. The present study was designed to disambiguate these alternative suggestions by implementing various constraints on planning time and by assessing self-reported motivation. In contrast to the previous study, chess players' performance was not superior, independently of whether problems had to be solved with (Experiment 1) or without (Experiment 2) time limits. As expected, chess players reported higher overall trait and state motivation scores across both experiments. These findings revise the notion of superior planning performance in chess players. In consequence, they do not conform with the assumption of a general transfer of chess-related planning expertise to other cognitive domains, instead suggesting that superior performance may be possible only under specific circumstances such as receiving competitive instructions.

Psychometric analyses of the Tower of London planning task reveal high reliability and feasibility in typically developing children and child patients with ASD and ADHD.

The Tower of London (TOL) is probably the most often used assessment tool for planning ability in healthy and clinical samples. Various versions, including our proposed standard problem set, have proven to be feasible and reliable in adults. In contrast, reliability information for typically developing (TD) children and neurodevelopmental disorders during childhood are largely missing. Also, it would be highly desirable to attain a problem set that can be used across the whole lifespan. Therefore, here we examine reliability of our proposed standard problem set using a computerized TOL version in 178 TD children (two different samples), 49 children with high-functioning autism spectrum disorder (ASD) and 56 children with attention-deficit/hyperactivity disorder (ADHD) (age ranges of each group 6 to 13 years), and 130 young adults (age range 18 to 32 years). Greatest lower bound estimates of reliability were adequate to high in the two samples of TD children (.76 and .80) and high to very high in patients (ASD: .90; ADHD: .83). In young adults, all reliability indices were adequate to high. Moreover, a subset of four- and five-move problems exhibited sufficient performance variability and high part-whole correlations with the complete problem set in all samples. These findings demonstrate the reliability of the presented TOL problem set in both clinical and non-clinical child samples. A clinically feasible subset of four- and five-move problems is reflective of overall planning performance at all ages, hence enabling comparisons of planning ability within and between developmental samples across almost the whole lifespan.

Intact Visuospatial Cognition in Amblyopia: Results From the Gutenberg Health Study.

PURPOSE: To determine whether amblyopia interferes with cognitive functions requiring visuospatial processing, measured by the Tower of London (ToL) test. METHODS: The current study was based on a sub-cohort from the population-based Gutenberg Health Study and included 1,569 participants aged 35 to 44 years. Amblyopia was defined as a visual acuity of 0.63 or worse (worse eye) in the presence of an amblyogenic factor; prevalence was 5%. There were three groups: participants with amblyopia (n = 78), participants with a visual acuity of 0.63 or worse (worse eye) without amblyopia (n = 65), and participants with a visual acuity of better than 0.63 (worse eye) (n = 1,426). Visuospatial planning ability was measured by the ToL test (touch-screen version), and the performance score ranged from 0 to 24, depending on the number of correctly solved problems. The authors used linear regression models to investigate the association between amblyopia and ToL test scores, adjusting for age, sex, and socioeconomic status. RESULTS: The mean ± standard deviation of ToL test performance was 15.31 ± 3.29 in participants with a visual acuity of better than 0.63, 14.56 ± 3.76 in the amblyopic group, and 15.14 ± 3.65 in participants with a visual acuity of 0.63 or worse without amblyopia. In a linear regression model, sex, and socioeconomic status significantly predicted planning performance (P <.0001), whereas amblyopic status did not (P = .20). CONCLUSIONS: Amblyopia may affect visuospatial perception, but no such relationships could be found for higher cognitive functions that strongly depend on visuospatial processing. Thus, in adulthood, individuals with amblyopia are unaffected in their visuospatial cognitive abilities, as required by the ToL test. [J Pediatr Ophthalmol Strabismus. 2019;56(6):397-401.].

Status and predictors of planning ability in adult long-term survivors of CNS tumors and other types of childhood cancer.

Long-term childhood cancer survivors' (CCS) quality of life can be impacted by late effects such as cognitive difficulties. Especially survivors of CNS tumors are assumed to be at risk, but reports of cognitive tests in CCS with survival times >25 years are scarce. We assessed planning ability, a capacity closely related to fluid intelligence, using the Tower of London. We compared 122 CNS tumor survivors, 829 survivors of other cancers (drawn from a register-based sample of adult long-term CCS), and 215 healthy controls (using sex-specific one-way ANOVAs and t-tests). Associations of CCS' planning ability with medical and psychosocial factors were investigated with a hierarchical linear regression analysis. Mean planning ability did not differ between CCS and controls. However, female CNS tumor survivors performed worse than female survivors of other cancers and female controls. CNS tumor survivors of both sexes had a lower socioeconomic status, and fewer of them had achieved high education than other survivors. In the regression analysis, lower status and anxiety symptoms were associated with poor planning, suggesting possible mediators of effects of disease and treatment. The results indicate the necessity to contextualize test results, and to include cognitive and psychological assessments into aftercare.

Thinking around the corner: the development of planning abilities.

The ability to plan and search ahead is essential for problem solving in most situations in everyday life. To investigate the development of planning and related processes, a sample of four- and five-year-old children was examined in a variant of the Tower of London, a frequently used neuropsychological assessment tool of planning abilities. The applied problems either required searching ahead for optimal solution or were solvable by pure step-by-step forward processing. Furthermore, the ambiguity of subgoal ordering was varied. Results revealed an age-related effect of search depth: the four-year olds' planning accuracy was particularly decreased in problems demanding search ahead, while five-year olds mastered both problem types equally well. Interestingly, this interaction between age and search depth could not be accounted for by measures of working memory and inhibition. Differential effects of age were also found for subgoal ordering with respect to initial planning and movement execution times. In sum, planning abilities showed considerable development during late kindergarten age that appeared to be specifically associated with the integration and back-validation of the anticipated consequences of internally modeled actions. The present study demonstrates that a careful consideration of problem structure may greatly enhance the insights gained from the application of a routinely used assessment tool, the Tower of London. This may be especially advantageous when addressing specific subpopulations such as children or clinical samples.

Inferior Frontal Gyrus Volume Loss Distinguishes Between Autism and (Comorbid) Attention-Deficit/Hyperactivity Disorder-A FreeSurfer Analysis in Children.

Objective: Autism spectrum (ASD) and attention-deficit/hyperactivity disorder (ADHD) are neurodevelopmental disorders with a high rate of comorbidity. To date, diagnosis is based on clinical presentation and distinct reliable biomarkers have been identified neither for ASD nor ADHD. Most previous neuroimaging studies investigated ASD and ADHD separately. Method: To address the question of structural brain differences between ASD and ADHD, we performed FreeSurfer analysis in a sample of children with ADHD (n = 30), with high-functioning ASD (n = 14), with comorbid high-functioning ASD and ADHD (n = 15), and of typically developed controls (TD; n = 36). With FreeSurfer, an automated brain imaging processing and analyzing suite, we reconstructed the cerebral cortex and calculated gray matter volumes as well as cortical surface parameters in terms of cortical thickness and mean curvature. Results: A significant main effect of the factor ADHD was detected for the left inferior frontal gyrus (Pars orbitalis) volume, with the ADHD group exhibiting smaller Pars orbitalis volumes. Dimensional measures of autism (SRS total raw score) and ADHD (DISYPS-II FBB-ADHD score) had no significant influence on the left Pars orbitalis volume. Both, ASD and ADHD tended to have an effect on cortical thickness or mean curvature, which did not survive correction for multiple comparisons. Conclusion: Our results underline that ADHD rather than ASD is associated with volume loss in the left inferior frontal gyrus (Pars orbitalis). This area might play a relevant role in modulating symptoms of inattention and/or impulsivity in ADHD. The effect of comorbid ADHD in ASD samples and vice versa, on cortical thickness and mean curvature, requires further investigation in larger samples.

Association of ocular, cardiovascular, morphometric and lifestyle parameters with retinal nerve fibre layer thickness.

BACKGROUND: Glaucoma is a neurodegenerative disease, leading to thinning of the retinal nerve fibre layer (RNFL). The exact influence of ocular, cardiovascular, morphometric, lifestyle and cognitive factors on RNFL thickness (RNFLT) is unknown and was analysed in a subgroup of the Gutenberg Health Study (GHS). METHODS: Global peripapillary RNFLT was measured in 3224 eyes of 1973 subjects (49% female) using spectral-domain optical coherence tomography (SD-OCT). The association of age, sex, ocular, cardiovascular, morphometric, lifestyle and cognitive factors on RNFLT was analysed using Pearson correlation coefficient and fitting a linear mixed model. RESULTS: In the univariable analysis highest correlations were found for axial length (r = -0.27), spherical equivalent (r = 0.24), and glaucoma (r = -0.15) (p<0.0001, respectively). Other significant correlations with RNFLT were found for age, sex, intraocular pressure, systemic hypertension and systolic blood pressure, previous eye surgery, cholesterol, homocysteine, history of coronary artery disease, history of myocardial infarction, apnoea, diabetes and alcohol intake, p<0.05, respectively. Body length, body weight, BMI, diastolic blood pressure, blood glucose, HbA1c, history of apoplexy, cognitive function, peripheral artery disease, tinnitus, migraine, nicotine intake, central corneal thickness, and pseudophakia were not significantly correlated with RNFLT. The regression model revealed a significant relationship between RNFLT and age in decades (p<0.02), spherical equivalent (p<0.0001), axial length (p<0.0001), glaucoma (p<0.0001), tinnitus (p = 0.04), apnoea (p = 0.047), homocysteine (p = 0.05) and alcohol intake >10g/d for women and >20g/d for men (p = 0.02). Glaucoma, apnoea, higher homocysteine, higher alcohol intake and higher axial length as well as age were related to decreased RNFLT while higher spherical equivalent or history for tinnitus were related to thicker RNFL. CONCLUSION: RNFLT is related to age, ocular parameters and lifestyle factors. Considering these parameters in normative databases could improve the evaluation of peripapillary RNFLT. It is necessary to evaluate if a reduction of alcohol intake as well as the therapy of apnea or high homocysteine levels could positively influence RNFLT.

Gender-related differences in lateralization of hippocampal activation and cognitive strategy.

Gender-related differences in brain activation patterns and their lateralization associated with cognitive functions have been reported in the field of language, emotion, and working memory. Differences have been hypothesized to be due to different cognitive strategies. The aim of the present study was to test whether lateralization of brain activation in the hippocampi during memory processing differs between the sexes. We acquired functional magnetic resonance imaging data from healthy female and male study participants performing a spatial memory task and quantitatively assessed the lateralization of hippocampal activation in each participant. Hippocampal activation was significantly more left lateralized in women, and more right lateralized in men. Correspondingly, women rated their strategy as being more verbal than men did.

Planning and problem solving: from neuropsychology to functional neuroimaging.

This article provides an overview of recent research on human planning and problem solving. As an introduction, these two cognitive domains will be described and discussed from the perspective of experimental and cognitive psychology. The following sections will focus on the role of the prefrontal cortex in planning and problem solving and on disorders of these functions in patients with frontal-lobe lesions. Specific emphasis will be placed on the Tower of London task, a well established and widely used neuropsychological test of planning ability. We will present an overview of recent behavioural and neuroimaging studies that have employed the Tower of London task to draw specific conclusions about the likely neural and cognitive basis of planning function. Finally, we turn to a number of new directions and recent studies exploring different aspects of planning and problem solving and their association to related cognitive dimensions.

Development of Planning in Children with High-Functioning Autism Spectrum Disorders and/or Attention Deficit/Hyperactivity Disorder.

Planning impairment is often observed in children with high-functioning autism spectrum disorders (ASD), but attempts to differentiate planning in ASD from children with attention deficit hyperactivity disorder (ADHD) and typically developing children (TD) have yielded inconsistent results. This study examined differences between these groups by focusing on development and analyzing performance in searching ahead several steps ("search depth") in addition to commonly used global performance measures in planning. A cross-sectional consecutive sample of 83 male patients (6-13 years), subgrouped as ASD without (ASD-, n = 18) or with comorbid ADHD (ASD+, n = 23), ADHD only (n = 42) and n = 42 TD children (6-13 years) were tested with the Tower-of-London-task. For global performance, ASD+ showed the lowest accuracy in younger children, but similar performance as TD at older ages, suggesting delayed development. Typically, a prolongation of planning time with increasing problem difficulty is observed in older children as compared to younger children. Here, this was most pronounced in ASD-, but under-expressed in ADHD. In contrast to global performance, effects of search depth were independent of age. ASD-, but not ASD+, showed increased susceptibility to raised demands on mentally searching ahead, along with the longest planning times. Thus, examining both global and search depth performance across ages revealed discernible patterns of planning between groups. Notably, the potentially detrimental impact of two diagnosed disorders does not add up in ASD+ in this task. Rather, our results suggest paradoxical enhancement of performance, ostensibly attributable to disruption of behavioral rigidity through increased impulsivity, which did not take place in ASD-. Autism Res 2016, 9: 739-751. © 2015 International Society for Autism Research, Wiley Periodicals, Inc.

Assessing Planning Ability Across the Adult Life Span: Population-Representative and Age-Adjusted Reliability Estimates for the Tower of London (TOL-F).

Planning ahead the consequences of future actions is a prototypical executive function. In clinical and experimental neuropsychology, disc-transfer tasks like the Tower of London (TOL) are commonly used for the assessment of planning ability. Previous psychometric evaluations have, however, yielded a poor reliability of measuring planning performance with the TOL. Based on theory-grounded task analyses and a systematic problem selection, the computerized TOL-Freiburg version (TOL-F) was developed to improve the task's psychometric properties for diagnostic applications. Here, we report reliability estimates for the TOL-F from two large samples collected in Mainz, Germany (n = 3,770; 40-80 years) and in Vienna, Austria (n = 830; 16-84 years). Results show that planning accuracy on the TOL-F possesses an adequate internal consistency and split-half reliability (>0.7) that are stable across the adult life span while the TOL-F covers a broad range of graded difficulty even in healthy adults, making it suitable for both research and clinical application.