Action control costs in task selection: Agents avoid actions with incompatible movement and effect features.

When a movement triggers effects with incompatible features, conflict between action and effect features creates costs for action planning and initiation. We investigated whether such action control costs also factor into action choices in terms of the principle of least effort. Participants completed a reaction-time experiment, where they were instructed to perform left and right mouse swipes in response to directional cues presented on the screen. Participants could select between two action options on each trial: Depending on which part of the screen (upper or lower) the action was performed in, the swipe resulted in a visual stimulus moving in the same (compatible) or in the opposite (incompatible) direction as the mouse. Incompatible action-effect mappings did indeed incur action control costs. In accordance with effort avoidance, the proportion of compatible choices was significantly above chance level, suggesting that action selection and initiation costs factor into participants preferences. Interestingly, however, participants' choice tendencies were not predicted by the actual increase in action-initiation costs in the incompatible condition. This indicates that effort-related decisions are not simply based on monitoring performance in the actual task, but they are also influenced by preestablished notions of action-planning costs.

Development of the mirror-image sensitivity for different object categories-Evidence from the mirror costs of object images in children and adults.

Object recognition relies on a multitude of factors, including size, orientation, and so on. Mirrored orientation, particularly due to children's mirror confusion in reading, holds special significance among various object orientations. Brain imaging studies suggest that the visual ventral and dorsal streams exhibit distinct orientation sensitivity across diverse object categories. Yet, it remains unclear whether mirror orientation sensitivity also varies among these categories during development at the behavioral level. Here, we explored the mirror sensitivity of children and adults across five distinct categories, which encompass tools that activate both the visual ventral stream for function information and the dorsal stream for manipulation information, and animals and faces that mainly activate the ventral stream. Two types of symbols, letters and Chinese characters, were also included. Mirror sensitivity was assessed through mirror costs-that is, the additional reaction time or error rate in the mirrored versus the same orientation condition when judging the identity of object pairs. The mirror costs in reaction times and error rates consistently revealed that children exhibited null mirror costs for tools, and the mirror costs for tools in adults were minimal, if any, and were smaller than those for letters and characters. The mirror costs reflected in absolute reaction time and error rate were similar across adults and children, but when the overall difference in reaction times was considered, adults showed a larger mirror cost than children. Overall, our investigation unveils categorical distinctions and development in mirror sensitivity of object recognition across the ventral and dorsal streams.

What is the prevalence of developmental prosopagnosia? An empirical assessment of different diagnostic cutoffs.

The prevalence of developmental prosopagnosia (DP), lifelong face recognition deficits, is widely reported to be 2-2.5%. However, DP has been diagnosed in different ways across studies, resulting in differing prevalence rates. In the current investigation, we estimated the range of DP prevalence by administering well-validated objective and subjective face recognition measures to an unselected web-based sample of 3116 18-55 year-olds and applying DP diagnostic cutoffs from the last 14 years. We found estimated prevalence rates ranged from .64-5.42% when using a z-score approach and .13-2.95% when using a percentile approach, with the most commonly used cutoffs by researchers having a prevalence rate of .93% (z-score, .45% when using percentiles). We next used multiple cluster analyses to examine whether there was a natural grouping of poorer face recognizers but failed to find consistent grouping beyond those with generally above versus below average face recognition. Lastly, we investigated whether DP studies with more relaxed diagnostic cutoffs were associated with better performance on the Cambridge Face Perception Test. In a sample of 43 studies, there was a weak nonsignificant association between greater diagnostic strictness and better DP face perception accuracy (Kendall's tau-b correlation, τb =.18 z-score; τb = .11 percentiles). Together, these results suggest that researchers have used more conservative DP diagnostic cutoffs than the widely reported 2-2.5% prevalence. We discuss the strengths and weaknesses of using more inclusive cutoffs, such as identifying mild and major forms of DP based on DSM-5.

Do Diacritics Entail an Early Processing Cost in the Absence of Abstract Representations? Evidence from Masked Priming in English.

Using the masked priming technique, word recognition experiments in various languages have shown slower response times for a target word like NEVEU (nephew, in French) when preceded by a diacritical prime like néveu than by the identity prime neveu. The most common account of this effect is linguistic: diacritical and non-diacritical vowels (e.g., é and e) activate different letter representations (e.g., compare neveu /nə.vø/ vs. néveu /ne.vø/). However, another explanation is that the reduced effectiveness of the diacritical primes is merely due to the perceptual salience of accent marks in the first moments of word processing. Here, we designed a masked priming experiment that tested this perceptual salience account by comparing the effectiveness of diacritical versus non-diacritical primes in a language where diacritics have no linguistic value, namely, English (e.g., nórth-NORTH vs. north-NORTH). We found a small but reliable cost due to the diacritical primes, thus revealing that perceptual salience reduced the effectiveness of the primes. However, the effect sizes were substantially smaller than in the experiments in languages with diacritical marks, thus suggesting that the néveu-NEVEU versus neveu-NEVEU difference relies on both linguistic and perceptual sources.

Web-based language production experiments: Semantic interference assessment is robust for spoken and typed response modalities.

For experimental research on language production, temporal precision and high quality of the recorded audio files are imperative. These requirements are a considerable challenge if language production is to be investigated online. However, online research has huge potential in terms of efficiency, ecological validity and diversity of study populations in psycholinguistic and related research, also beyond the current situation. Here, we supply confirmatory evidence that language production can be investigated online and that reaction time (RT) distributions and error rates are similar in written naming responses (using the keyboard) and typical overt spoken responses. To assess semantic interference effects in both modalities, we performed two pre-registered experiments (n = 30 each) in online settings using the participants' web browsers. A cumulative semantic interference (CSI) paradigm was employed that required naming several exemplars of semantic categories within a seemingly unrelated sequence of objects. RT is expected to increase linearly for each additional exemplar of a category. In Experiment 1, CSI effects in naming times described in lab-based studies were replicated. In Experiment 2, the responses were typed on participants' computer keyboards, and the first correct key press was used for RT analysis. This novel response assessment yielded a qualitatively similar, very robust CSI effect. Besides technical ease of application, collecting typewritten responses and automatic data preprocessing substantially reduce the work load for language production research. Results of both experiments open new perspectives for research on RT effects in language experiments across a wide range of contexts. JavaScript- and R-based implementations for data collection and processing are available for download.

Effects of horizontal displacement and inter-character spacing on transposed-character effects in same-different matching.

In two same-different matching experiments we investigated whether transposed-character effects can be modulated by the horizontal displacement or inter-character spacing of target stimuli (strings of 6 consonants, digits, or symbols). Reference and target stimuli could be identical or differed either by transposing or substituting two characters. Transposition costs (greater difficulty in detecting a difference with transpositions compared with substitutions) were greater for letter stimuli compared to both digit and symbol stimuli in both experiments. In Experiment 1, half of the targets were displayed at the center of the screen and the other half were shifted by two character-positions to the left or to the right, whereas the reference was always presented at the center of the screen. Target displacement made the task harder and caused an increase in transposition costs whatever the type of stimulus. In Experiment 2, all stimuli were presented at the center of the screen and the inter-character spacing of target stimuli was increased by one character space on half of the trials. Increased spacing made the task harder and paradoxically caused an increase in transposition costs, but only significantly so for letter stimuli, and only in the discriminability (d') measure. These results suggest that target location and inter-character spacing manipulations caused an increase in positional uncertainty during the processing of location-specific complex features prior to activation of a location-invariant representation of character-in-string order. The hypothesized existence of a letter-specific order encoding mechanism accounts for the greater transposition costs seen with letter stimuli, as well as the greater modulation of these effects by an increase in inter-character spacing seen in discriminability (d').

Similarities and disparities between visual analysis and high-resolution electromyography of facial expressions.

Computer vision (CV) is widely used in the investigation of facial expressions. Applications range from psychological evaluation to neurology, to name just two examples. CV for identifying facial expressions may suffer from several shortcomings: CV provides indirect information about muscle activation, it is insensitive to activations that do not involve visible deformations, such as jaw clenching. Moreover, it relies on high-resolution and unobstructed visuals. High density surface electromyography (sEMG) recordings with soft electrode array is an alternative approach which provides direct information about muscle activation, even from freely behaving humans. In this investigation, we compare CV and sEMG analysis of facial muscle activation. We used independent component analysis (ICA) and multiple linear regression (MLR) to quantify the similarity and disparity between the two approaches for posed muscle activations. The comparison reveals similarity in event detection, but discrepancies and inconsistencies in source identification. Specifically, the correspondence between sEMG and action unit (AU)-based analyses, the most widely used basis of CV muscle activation prediction, appears to vary between participants and sessions. We also show a comparison between AU and sEMG data of spontaneous smiles, highlighting the differences between the two approaches. The data presented in this paper suggests that the use of AU-based analysis should consider its limited ability to reliably compare between different sessions and individuals and highlight the advantages of high-resolution sEMG for facial expression analysis.

Cumulative semantic cost without successful naming.

Accessing semantic information has negative consequences for successive recovering attempts of similar information. For instance, in the course of picture-naming tasks, the time required to name an object is determined by the total number of items from the same category that have already been named; naming latencies increase proportionally to the total number of semantically related words named previously. This phenomenon is called cumulative semantic cost (or interference). Two picture-naming experiments with children (4-11 years old, 229 participants) investigate whether having successfully named the previous within-category items is a necessary condition for the cumulative semantic cost to appear. We anticipated that younger children would have a larger rate of nonresponses compared with older children, reflecting the fact that younger children have not yet consolidated many lexical representations. Our results confirmed this prediction. Critically, we also observed that cumulative semantic cost was independent of having successfully retrieved previous within-category lexical items. Furthermore, picture trials for which the previous within-category item elicited a nonresponse showed the same amount of cost as those picture trials for which the previous within-category item elicited a correct naming event. Our findings indicate that it is the attempt to retrieve a lexical unit, and not the successful retrieval of a specific lexical unit, that causes semantic cost in picture naming. This cost can be explained by a mechanism of weakening the semantic-to-lexical mappings of semantic coordinate words. The findings are also discussed in the context of retrieval-induced forgetting effects in memory recall research.

Rapid online assessment of reading ability.

An accurate model of the factors that contribute to individual differences in reading ability depends on data collection in large, diverse and representative samples of research participants. However, that is rarely feasible due to the constraints imposed by standardized measures of reading ability which require test administration by trained clinicians or researchers. Here we explore whether a simple, two-alternative forced choice, time limited lexical decision task (LDT), self-delivered through the web-browser, can serve as an accurate and reliable measure of reading ability. We found that performance on the LDT is highly correlated with scores on standardized measures of reading ability such as the Woodcock-Johnson Letter Word Identification test (r = 0.91, disattenuated r = 0.94). Importantly, the LDT reading ability measure is highly reliable (r = 0.97). After optimizing the list of words and pseudowords based on item response theory, we found that a short experiment with 76 trials (2-3 min) provides a reliable (r = 0.95) measure of reading ability. Thus, the self-administered, Rapid Online Assessment of Reading ability (ROAR) developed here overcomes the constraints of resource-intensive, in-person reading assessment, and provides an efficient and automated tool for effective online research into the mechanisms of reading (dis)ability.

Do portrait artists have enhanced face processing abilities? Evidence from hidden Markov modeling of eye movements.

Recent research has suggested the importance of part-based information in face recognition in addition to global, whole-face information. Nevertheless, face drawing experience was reported to enhance selective attention to the eyes but did not improve face recognition performance, leading to speculations about limited plasticity in adult face recognition. Here we examined the mechanism underlying the limited advantage of face drawing experience in face recognition through the Eye Movement analysis with Hidden Markov Models (EMHMM) approach. We found that portrait artists showed more eyes-focused eye movement patterns and outperformed novices in face matching, and participants' drawing rating was correlated with both eye movement pattern and performance. In contrast, portrait artists did not outperform novices and did not differ from novices in eye movement pattern in either the face recognition or part-whole tasks, although the eyes-focused pattern was associated with better recognition performance and longer response times in the whole condition relative to the part condition. Interestingly, in contrast to the face recognition and part-whole tasks, participants' performance in face matching was predicted by their drawing rating but not eye movement pattern. These results suggested that artists' advantage in face processing is specific to tasks similar to their drawing experience such as face matching, and may be related to their better ability in extracting identity-invariant information between two faces rather than more eyes-focused eye movement patterns.

Parafoveal degradation during reading reduces preview costs only when it is not perceptually distinct.

There is a growing understanding that the parafoveal preview effect during reading may represent a combination of preview benefits and preview costs due to interference from parafoveal masks. It has been suggested that visually degrading the parafoveal masks may reduce their costs, but adult readers were later shown to be highly sensitive to degraded display changes. Four experiments examined how preview benefits and preview costs are influenced by the perception of distinct parafoveal degradation at the target word location. Participants read sentences with four preview types (identity, orthographic, phonological, and letter-mask preview) and two levels of visual degradation (0% vs. 20%). The distinctiveness of the target word degradation was either eliminated by degrading all words in the sentence (Experiments 1a-2a) or remained present, as in previous research (Experiments 1b-2b). Degrading the letter masks resulted in a reduction in preview costs, but only when all words in the sentence were degraded. When degradation at the target word location was perceptually distinct, it induced costs of its own, even for orthographically and phonologically related previews. These results confirm previous reports that traditional parafoveal masks introduce preview costs that overestimate the size of the true benefit. However, they also show that parafoveal degradation has the unintended consequence of introducing additional costs when participants are aware of distinct degradation on the target word. Parafoveal degradation appears to be easily perceived and may temporarily orient attention away from the reading task, thus delaying word processing.

The differential impact of viewing fitspiration and thinspiration images on men's body image concerns: An experimental ecological momentary assessment study.

To date, little is known about the impact of fitspiration and thinspiration exposure on men, as previous studies on these social media trends were primarily conducted on women. Male participants (n = 223) completed baseline measures of trait body image, then used a smartphone application to complete up to six state-based assessments daily for seven days. In each assessment, participants were randomly assigned to one of three image conditions (fitspiration, thinspiration, or neutral). Before and after viewing each image, they reported state body fat dissatisfaction, muscularity dissatisfaction, negative mood, and urge to engage in behaviours to reduce body fat and increase muscularity. Multi-level analyses revealed that compared to viewing neutral images, viewing fitspiration images increased men's body dissatisfaction, whereas viewing thinspiration images decreased body dissatisfaction. Viewing either fit- or thinspiration images also led to lower mood and greater urges to increase muscularity, whereas only fitspiration images increased urges to reduce body fat. Men with greater baseline muscularity dissatisfaction and higher appearance comparison were most vulnerable to muscularity dissatisfaction after viewing fitspiration images. Findings suggest the importance of limiting exposure to fitspiration imagery and implementing social media literacy programmes for men and well as women.

Vision for the blind: visual psychophysics and blinded inference for decision models.

Evidence accumulation models like the diffusion model are increasingly used by researchers to identify the contributions of sensory and decisional factors to the speed and accuracy of decision-making. Drift rates, decision criteria, and nondecision times estimated from such models provide meaningful estimates of the quality of evidence in the stimulus, the bias and caution in the decision process, and the duration of nondecision processes. Recently, Dutilh et al. (Psychonomic Bulletin & Review 26, 1051-1069, 2019) carried out a large-scale, blinded validation study of decision models using the random dot motion (RDM) task. They found that the parameters of the diffusion model were generally well recovered, but there was a pervasive failure of selective influence, such that manipulations of evidence quality, decision bias, and caution also affected estimated nondecision times. This failure casts doubt on the psychometric validity of such estimates. Here we argue that the RDM task has unusual perceptual characteristics that may be better described by a model in which drift and diffusion rates increase over time rather than turn on abruptly. We reanalyze the Dutilh et al. data using models with abrupt and continuous-onset drift and diffusion rates and find that the continuous-onset model provides a better overall fit and more meaningful parameter estimates, which accord with the known psychophysical properties of the RDM task. We argue that further selective influence studies that fail to take into account the visual properties of the evidence entering the decision process are likely to be unproductive.

Grading Gliomas Capability: Comparison between Visual Assessment and Apparent Diffusion Coefficient (ADC) Value Measurement on Diffusion-Weighted Imaging (DWI).

BACKGROUND: To compare diagnostic accuracy between DWI visual scale assessment and ADC value measurement of solid portion of the tumor in grading gliomas. METHODS: This retrospective study included 38 patients who had pathologically proven gliomas between January 2013 and August 2018 with 18 low grade and 20 high grade tumors. All patients underwent MRI and biopsy. Two readers reviewed DWI visual scale independently. Disagreement was resolved by consensus. One reviewer measured ADC value of entire solid part of the tumor in single axial slice with greatest dimension of tumor which was chosen by consensus. Two data sets of visual scale and ADC value were analyzed and comparison of diagnostic accuracy in glioma grading was done by using area under the curve (AUC) of receiver operating characteristic curve (ROC). RESULTS: Visual scale and ADC value could be used to distinguish between low and high grade gliomas with a statistically significant difference. (P-value 0.002 and <0.001). Almost all high grade gliomas had visual scale 5. The sensitivity, specificity, PPV NPV and accuracy were 50%, 100%, 100% , 64.3%,73.68% respectively. The cutoff level for the ADC value was determined to be 1119.48 x10-6 mm2/s in differentiation between low and high grade gliomas with the sensitivity, specificity, PPV, NPV, accuracy of 90%, 88.89% , 90%, 88.9% and 89.47% respectively. There was no statistically significant difference(P-value = 0.163). CONCLUSION: Both Visual scale and ADC value were capable of differentiating between low and high grade gliomas. Although visual scale may not replace ADC measurement, larger scale prospective study is needed for validate this initial result.
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Multi-domain cognitive assessment of male mice shows space radiation is not harmful to high-level cognition and actually improves pattern separation.

Astronauts on interplanetary missions - such as to Mars - will be exposed to space radiation, a spectrum of highly-charged, fast-moving particles that includes 56Fe and 28Si. Earth-based preclinical studies show space radiation decreases rodent performance in low- and some high-level cognitive tasks. Given astronaut use of touchscreen platforms during training and space flight and given the ability of rodent touchscreen tasks to assess functional integrity of brain circuits and multiple cognitive domains in a non-aversive way, here we exposed 6-month-old C57BL/6J male mice to whole-body space radiation and subsequently assessed them on a touchscreen battery. Relative to Sham treatment, 56Fe irradiation did not overtly change performance on tasks of visual discrimination, reversal learning, rule-based, or object-spatial paired associates learning, suggesting preserved functional integrity of supporting brain circuits. Surprisingly, 56Fe irradiation improved performance on a dentate gyrus-reliant pattern separation task; irradiated mice learned faster and were more accurate than controls. Improved pattern separation performance did not appear to be touchscreen-, radiation particle-, or neurogenesis-dependent, as 56Fe and 28Si irradiation led to faster context discrimination in a non-touchscreen task and 56Fe decreased new dentate gyrus neurons relative to Sham. These data urge revisitation of the broadly-held view that space radiation is detrimental to cognition.

Assessment tool for visual perception deficits in cerebral visual impairment: development and normative data of typically developing children.

AIM: To develop an assessment tool that measures a wide range of visual perceptual deficits common in cerebral visual impairment (CVI) and to provide normative data from typically developing children between 3 and 6 years of age. METHOD: Test development reflected cross-talk between vision research and clinical relevance for CVI. The Children's Visual Impairment Test for 3- to 6-year-olds (CVIT 3-6) includes 14 subtests covering four domains of visual perception: Object Recognition, Degraded Object Recognition, Motion Perception, and Global-Local Processing. Normative data were collected from 301 typically developing children (mean age 4y 8mo [SD 9.7mo]; 148 females, 153 males). A questionnaire was administered to parents about pregnancy duration, birth, and developmental problems. RESULTS: Average total CVIT 3-6 performance was 60.1 (SD 5.5) out of 70. The cut-off score for normal visual perception (53) was set at the 10th centile of scores in typically developing children. Multiple regression indicated CVIT 3-6 visual perception scores increase with age for children born at 36 weeks' gestational age or later (ß=-18.03, 95% confidence interval -31.31 to -4.75). INTERPRETATION: CVIT 3-6 is a tool to assess a wide range of visual perceptual deficits common in CVI. Age-dependent normative data are available because we found performance increased with age. WHAT THE PAPER ADDS: A test for visual perceptual deficits common in cerebral visual impairment. Visual perceptual functions improve with age in full-term typically developing children.

HERRAMIENTA DE EVALUACIÓN PARA LAS DEFICIENCIAS DE LA PERCEPCIÓN VISUAL EN LA DISCAPACIDAD VISUAL CEREBRAL: DESARROLLO Y DATOS NORMATIVOS DE NIÑOS CON DESARROLLO TÍPICO: OBJETIVO: Desarrollar una herramienta de evaluación que mida una amplia gama de déficits de percepción visual comunes en la discapacidad visual cerebral (CVI) y proporcionar datos normativos de niños con un desarrollo típico entre los 3 y los 6 años de edad. MÉTODO: El desarrollo de la prueba reflejó la alineación de contenidos entre la investigación de la visión y la relevancia clínica para la CVI. La prueba de discapacidad visual para niños de 3 a 6 años (CVIT 3-6) incluye 14 subpruebas que cubren cuatro dominios de la percepción visual: reconocimiento de objetos, reconocimiento de objetos con fondos borrosos, percepción de movimiento y procesamiento global y local. Se recopilaron datos normativos de 301 niños con desarrollo típico (edad promedio 4 años y 8 meses [DS 9,7 meses]; 148 mujeres, 153 varones). Se administró un cuestionario a los padres sobre la duración del embarazo, el parto y los problemas de desarrollo. RESULTADOS: El rendimiento promedio total de CVIT 3-6 fue de 60,1 (DS 5,5) sobre 70. El puntaje límite para la percepción visual normal (53) se estableció en el décimo centil de puntajes en niños con un desarrollo típico. La regresión múltiple indicó que las puntuaciones de percepción visual CVIT 3-6 aumentan con la edad para los niños nacidos a las 36 semanas de edad gestacional o más tarde (ß = -18,03, intervalo de confianza del 95% -31,31 a -4,75). INTERPRETACIÓN: CVIT 3-6 es una herramienta para evaluar una amplia gama de déficits de percepción visual comunes en la CVI. Los datos normativos que dependen de la edad están disponibles porque encontramos que el rendimiento aumentó con la edad.

INSTRUMENTO DE AVALIAÇÃO PARA DÉFICITS DE PERCEPÇÃO VISUAL NA DEFICIÊNCIA VISUAL CEREBRAL: DESENVOLVIMENTO E DADOS NORMATIVOS DE CRIANÇAS COM DESENVOLVIMENTO TÍPICO: OBJETIVO: Desenvolver um instrumento de avaliação que mensure uma variedade de déficits de percepção visual comuns na deficiência visual cerebral (DVC) e fornecer dados normativos de crianças com desenvolvimento típcico entre 3 e 6 anos de idade. MÉTODO: O desenvolvimento do teste refletiu a comunicação entre pesquisas relacionadas à visão e a relevância clínica para a DVC. O Teste da Deficiência Visual para Crianças direcionado para a população de 3 a 6 anos de idade (TDVC-3-6) inclui 14 subtestes que cobrem quatro domínios da percepção visual: reconhecimento de objetos, reconhecimento de objetos diminuída, percepção de movimento, e processamento global-local. Dados normativos foram coletados em 301 crianças com desenvolvimento típico (média de idade 4a 8m [DP 9,7 m]; 148 do sexo feminino, 153 do sexo masculino). Um questionário foi administrado aos pais sobre a duração da gestação, nascimento e problemas relacionados ao desenvolvimento. RESULTADOS: O desempenho médio total no TDVC 3-6 foi 60,1 (DP 5,5) em um total de 70. O escore de corte para percepção visual normal (53) foi estabelecido como o 10o. percentil de escores em crianças com desenvolvimento típico. Regressão múltipla indicou que escores de percepção do TDVC 3-6 aumentam com a idade para crianças nascidas com 36 semanas de idade gestacional ou mais (ß=-18,03, 95% intervalo de confiança -31,31 a -4,75). INTERPRETAÇÃO: O TDVC 3-6 é um instrumento para avaliar uma variedade de déficits da percepção visual comuns em DVC. Dados normativos relacionados à idade estão disponíveis, pois observamos que o desempenho aumentou com a idade.

The benefit (and cost) of drawing as an encoding strategy.

Drawing, as an encoding strategy for to-be-remembered words, has previously been shown to provide robust memory benefits. In the current study, we investigated the effect of drawing on false memory endorsements during a recognition test. We found that while drawing led to higher hit rates relative to writing (Experiment 1) and creating visual mental imagery (Experiment 2), it also led to higher false alarm (FA) rates to critical lures in a variant of the Deese-Roediger-McDermott (DRM) paradigm. When compared with an encoding strategy requiring listing of object features (Experiment 3), drawing led to a lower FA rate. We suggest that drawing enhances memory by promoting recollection of rich visual contextual information during retrieval, and this leads to the unintended side effect of increasing FA rates to related information.

Estimating statistical power for event-related potential studies using the late positive potential.

The late positive potential (LPP) is a common measurement used to study emotional processes of subjects in ERP paradigms. Despite its extensive use in affective neuroscience, there is presently no gold standard for how to appropriately power ERP studies using the LPP. The present study investigates how the number of trials, number of subjects, and magnitude of the effect size affect statistical power in analyses of the LPP. Using Monte Carlo simulations of ERP experiments with varying numbers of trials, subjects, and synthetic effects of known magnitude, we measured the probability of obtaining a statistically significant effect in 1,489 experiments repeated 1,000 times each. Predictably, our results showed that statistical power increases with increasing numbers of trials and subjects and at larger effect sizes. We also found that higher levels of statistical power can be achieved with lower numbers of subjects and trials and at lower effect sizes in within-subject than in between-subjects designs. Furthermore, we found that, as subjects are added to an experiment, the slope of the relationship between effect size and statistical power increased and shifted to the left until the power asymptoted to nearly 100% at higher effect sizes. This suggests that adding more subjects greatly increases statistical power at lower effect sizes (<1 µV) compared with more robust (>1.5 µV) effect sizes. We confirmed the results from the simulations based on the synthetic effects by running a new series of simulated experiments based on real data collected while participants looked at emotional images.

Analysing linear multivariate pattern transformations in neuroimaging data.

Most connectivity metrics in neuroimaging research reduce multivariate activity patterns in regions-of-interests (ROIs) to one dimension, which leads to a loss of information. Importantly, it prevents us from investigating the transformations between patterns in different ROIs. Here, we applied linear estimation theory in order to robustly estimate the linear transformations between multivariate fMRI patterns with a cross-validated ridge regression approach. We used three functional connectivity metrics that describe different features of these voxel-by-voxel mappings: goodness-of-fit, sparsity and pattern deformation. The goodness-of-fit describes the degree to which the patterns in an input region can be described as a linear transformation of patterns in an output region. The sparsity metric, which relies on a Monte Carlo procedure, was introduced in order to test whether the transformation mostly consists of one-to-one mappings between voxels in different regions. Furthermore, we defined a metric for pattern deformation, i.e. the degree to which the transformation rotates or rescales the input patterns. As a proof of concept, we applied these metrics to an event-related fMRI data set consisting of four subjects that has been used in previous studies. We focused on the transformations from early visual cortex (EVC) to inferior temporal cortex (ITC), fusiform face area (FFA) and parahippocampal place area (PPA). Our results suggest that the estimated linear mappings explain a significant amount of response variance in the three output ROIs. The transformation from EVC to ITC shows the highest goodness-of-fit, and those from EVC to FFA and PPA show the expected preference for faces and places as well as animate and inanimate objects, respectively. The pattern transformations are sparse, but sparsity is lower than would have been expected for one-to-one mappings, thus suggesting the presence of one-to-few voxel mappings. The mappings are also characterised by different levels of pattern deformations, thus indicating that the transformations differentially amplify or dampen certain dimensions of the input patterns. While our results are only based on a small number of subjects, they show that our pattern transformation metrics can describe novel aspects of multivariate functional connectivity in neuroimaging data.

Attentional flexibility is imbalanced: Asymmetric cost for switches between external and internal attention.

Whereas the effects of attention switches occurring within perception or memory are relatively well understood, much less is known about switches of attention between them. We discuss the methodological limitations of initial research on this topic, which was never integrated with the broader cognitive literature. On the basis of this discussion, we present here a new paradigm, in which participants performed a simple probe-to-target matching task where targets were either perceived on screen or retrieved from memory. Across successive trials, repetitions or alternations (in both directions) between these 2 conditions were created, and eventually compared with each other. In line with our prediction, derived from the assumption of a top-down control mechanism, we found a cost for switching between external and internal attention in Experiment 1. Furthermore, this switch cost was asymmetric, being substantially larger when switching from (external) perception to (internal) memory than the other way around. In Experiments 2-4, we ruled out an imbalance in practice, learning, and preparation as confounds for this asymmetry. We propose that switches of attention between internal and external information are underpinned by a supervisory attention control mechanism, and that this asymmetry can be explained in terms of priming, associative interference or memory retrieval. (PsycINFO Database Record (c) 2019 APA, all rights reserved).