Don't SNARC me now! Intraindividual variability of cognitive phenomena - Insights from the Ironman paradigm.

Two implicit generalizations are often made from group-level studies in cognitive experimental psychology and their common statistical analysis in the general linear model: (1) Group-level phenomena are assumed to be present in every participant with variations between participants being often treated as random error in data analyses; (2) phenomena are assumed to be stable over time. In this preregistered study, we investigated the validity of these generalizations in the commonly used parity judgment task. In the proposed Ironman paradigm, the intraindividual presence and stability of three popular numerical cognition effects were tested in 10 participants on 30 days: the SNARC (Spatial-Numerical Association of Response Codes, i.e., faster left-/right-sided responses to small/large magnitude numbers, respectively; Dehaene, Bossini, & Giraux, 1993), MARC (Linguistic Markedness of Response Codes; i.e., faster left-/right-sided responses to odd/even numbers, respectively; Nuerk, Iversen, & Willmes, 2004), and Odd (i.e., faster responses to even numbers; Hines, 1990) effects. We replicated the group-level effects; however, they were reliably present in only four to five (SNARC), six (MARC) or five (Odd) of 10 participants. Fluctuations seemed unsystematic, although the SNARC effect decreased over time along with reaction times. No correlation between the SNARC and MARC effects and sleep duration, tiredness, daytime, and consumption of stimulants were detected in most participants. These results challenge the frequent generalizations from group-level phenomena to individual participants and from single sessions to typical behavior. The innovative Ironman paradigm combined with bootstrap analyses permits unique insights into the intraindividual presence and stability of cognitive phenomena.

Silvia De Marchi (1929) on numerical estimation: A translation and commentary.

Vittorio Benussi (1878-1927) is known for numerous studies on optical illusions, visual and haptic perception, spatial and time perception. In Padova, he had a brilliant student who carefully worked on the topic of how people estimate numerosity, Silvia De Marchi (1897-1936). Her writings have never been translated into English before. Here we comment on her work and life, characterized also by the challenges faced by women in academia. The studies on perception of numerosity from her thesis were published as an article in 1929. We provide a translation from Italian, a redrawing of its 23 illustrations and of the graphs. It shows an original experimental approach and an anticipation of what later became known as magnitude estimation.

Bayesian evidence synthesis as a flexible alternative to meta-analysis: A simulation study and empirical demonstration.

Synthesizing results across multiple studies is a popular way to increase the robustness of scientific findings. The most well-known method for doing this is meta-analysis. However, because meta-analysis requires conceptually comparable effect sizes with the same statistical form, meta-analysis may not be possible when studies are highly diverse in terms of their research design, participant characteristics, or operationalization of key variables. In these situations, Bayesian evidence synthesis may constitute a flexible and feasible alternative, as this method combines studies at the hypothesis level rather than at the level of the effect size. This method therefore poses less constraints on the studies to be combined. In this study, we introduce Bayesian evidence synthesis and show through simulations when this method diverges from what would be expected in a meta-analysis to help researchers correctly interpret the synthesis results. As an empirical demonstration, we also apply Bayesian evidence synthesis to a published meta-analysis on statistical learning in people with and without developmental language disorder. We highlight the strengths and weaknesses of the proposed method and offer suggestions for future research.

Do we perceive sensations inside and outside of our body differently? Perceptual, emotional, and behavioral differences between visceral and somatic sensation, discomfort, and pain.

BACKGROUND: Experimental research evaluating differences between the visceral and somatic stimulation is limited to pain and typically uses different induction methods for visceral and somatic stimulation (e.g., rectal balloon distention vs. tactile hand stimulation). Our study aimed to compare differences in response time, intensity, unpleasantness, and threat between identical electrical visceral and somatic stimulations at both painful and non-painful perceptual thresholds. METHODS: Electrical stimulation was applied to the wrist and distal esophagus in 20 healthy participants. A double pseudorandom staircase determined perceptual thresholds of Sensation, Discomfort, and Pain for the somatic and visceral stimulations, separately. Stimulus reaction time (ms, via button press), and intensity, unpleasantness, and threat ratings were recorded after each stimulus. General linear mixed models compared differences in the four outcomes by stimulation type, threshold, and the stimulation type-by-threshold interaction. Sigmoidal maximum effect models evaluated differences in outcomes across all delivered stimulation intensities. KEY RESULTS: Overall, visceral stimulations were perceived as more intense, threatening, and unpleasant compared to somatic stimulations, but participants responded faster to somatic stimulations. There was no significant interaction effect, but planned contrasts demonstrated differences at individual thresholds. Across all delivered intensities, higher intensity stimulations were needed to reach the half-maximum effect of self-reported intensity, unpleasantness, and threat ratings in the visceral domain. CONCLUSIONS AND INFERENCES: Differences exist between modalities for both non-painful and painful sensations. These findings may have implications for translating paradigms and behavioral treatments from the somatic domain to the visceral domain, though future research in larger clinical samples is needed.

Cognitive archaeology, and the psychological assessment of extinct minds.

Evolutionary anthropology relies on both neontological and paleontological information. In the latter case, fields such as paleoneurology, neuroarchaeology, and cognitive archaeology are supplying new perspectives in prehistory and neuroscience. Cognitive archaeology, in particular, investigates the behaviors associated with extinct species or cultures according to specific psychological models. For example, changes in working memory, attention, or visuospatial integration can be postulated when related behavioral changes are described in the archaeological record. However, cognition is a process based on different and partially independent functional elements, and extinct species could hence have evolved distinct combinations of cognitive abilities or features, based on both quantitative and qualitative differences. Accordingly, differences in working memory can lead to more conceptual or more holistic mindsets, with important changes in the perception and management of the mental experience. The parietal cortex is particularly interesting, in this sense, being involved in functions associated with body-tool integration, attention, and visual imaging. In some cases, evolutionary mismatches among these elements can induce drawbacks that, despite their positive effects on natural selection, can introduce important constraints in our own mental skills. Beyond the theoretical background, some hypotheses can be tested following methods in experimental psychology. In any case, theories in cognitive evolution must acknowledge that, beyond the brain and its biology, the human mind is also deeply rooted in body perception, in social networks, and in technological extension.

Quality-Adjusted Life Year Proxies for Caries in Primary Dentition: A Discrete Choice Experiment.

INTRODUCTION: Cost-utility analysis (CUA)-a method to evaluate intervention cost-effectiveness-transforms benefits of alternatives into a measure of quantity and quality of life, such as quality-adjusted life year (QALY), to enable comparison across heterogeneous programs. Measurement challenges prevent directly estimating utilities and calculating QALYs for caries in primary dentition. Proxy disease QALYs are often used as a substitute; however, there lacks quantitative evidence that these proxy diseases are comparable to caries. OBJECTIVE: To employ a discrete choice experiment (DCE) to quantitatively determine the most comparable proxy disease for different levels of caries in primary dentition. METHODS: A cross-sectional DCE survey was administered to respondents (N = 461) who resided in California, were aged ≥18 y, and were primary caretakers for ≥1 child aged 3 to 12 y. Four attributes were included: pain level, disease duration, treatment cost, and family life impacts. Mixed effects logistic regression and conditional logistic regression were used to analyze the survey data. RESULTS: Respondents from the overall sample preferred no pain over mild (odds ratio [OR] = 0.50, P < 0.05), moderate (OR = 0.57, P < 0.05), and severe pain (OR = 0.48, P < 0.05). Acute gastritis (OR = 0.44, P < 0.05), chronic gastritis (OR = 0.31, P < 0.01), and cold sore (OR = 0.38, P < 0.05) were less preferred than stage 1 caries. Acute tonsilitis (OR = 0.43, P < 0.05), acute gastritis (OR = 0.38, P < 0.05), chronic gastritis (OR = 0.26, P < 0.01), and cold sore (OR = 0.33, P < 0.01) were less preferred than stage 2 caries. Chronic gastritis (OR = 0.42,P < 0.05) was less preferred than stage 4 caries. CONCLUSIONS: Parents viewed the characteristics of many diseases with similar QALYs differently. Findings suggest that otitis media and its QALY-as commonly used in CUAs-may be a suitable proxy disease and substitute. However, other disease states with slightly different QALYs may be suitable. As such, the recommendation is to consider a range of proxy diseases and their QALYs when conducting a CUA for child caries interventions. KNOWLEDGE TRANSFER STATEMENT: This study reviews and systematically compares pediatric diseases that are comparable to caries in primary dentition. The findings may inform future research using cost-utility analysis to examine the incremental cost-effectiveness ratio of interventions to prevent and treat caries as compared with an alternative.

The timing database: An open-access, live repository for interval timing studies.

Interval timing refers to the ability to perceive and remember intervals in the seconds to minutes range. Our contemporary understanding of interval timing is derived from relatively small-scale, isolated studies that investigate a limited range of intervals with a small sample size, usually based on a single task. Consequently, the conclusions drawn from individual studies are not readily generalizable to other tasks, conditions, and task parameters. The current paper presents a live database that presents raw data from interval timing studies (currently composed of 68 datasets from eight different tasks incorporating various interval and temporal order judgments) with an online graphical user interface to easily select, compile, and download the data organized in a standard format. The Timing Database aims to promote and cultivate key and novel analyses of our timing ability by making published and future datasets accessible as open-source resources for the entire research community. In the current paper, we showcase the use of the database by testing various core ideas based on data compiled across studies (i.e., temporal accuracy, scalar property, location of the point of subjective equality, malleability of timing precision). The Timing Database will serve as the repository for interval timing studies through the submission of new datasets.

Music in an Emergent History of Psychology.

From a historical perspective, 'psychology' can be studied from an abundance of angels. Thus, a selected perspective requires some historiographical reflections, but also a conscious awareness of the actual chosen terms that are at stake. In this study, the historiographical perspective follows an emergent understanding of the history, which implies that the actual chosen terms are dynamically contributing to a web of terms, in which all of them may change in more or less unpredictable directions. In line with this, the aspect of music is consciously chosen, as it probably is one of the most ignored aspects of psychology in historical research. Thus, the findings in this study reveal that music as the 'direct factor' played an overarching role in the nineteenth centuries experimental psychology, but also that the changes in the understanding of music in the early sixteenth century is comparable with the changes the understanding of the soul underwent along with the introduction of the neologism 'psychology'. In the understanding of both music and the soul the sensational aspects replaced the mathematical.

Reception of experimental pedagogy and psychology in Chile. Analysis of the intellectual influences of Wilhelm Mann, 1904-1915.

This article provides a detailed analysis of the intellectual research project of Wilhelm Mann, one of the pioneers of experimental and educational psychology in Chile. Mann's work has been the object of so little analysis that his intellectual influences and networks are not clearly known. We analyzed 338 intratext citations from 22 works by Wilhelm Mann published during the period 1904-1915. As a result, we obtained a mapping of his cooperation networks and used a quantitative approach to study the authors who most influenced his career, among whom were William Stern, Herbert Spencer, Wilhelm Wundt, Alfred Binet, and Ernst Meumann. Mann was closely connected to the international and contemporary advances and discussions of his time, despite the lack of infrastructure and difficulties in communication. Mann was the first psychologist to develop a long-term project in Chile that aimed to measure the individualities of Chilean students and their intellectual development.

Editorial for Special Issue "Psychophysiology and Experimental Psychology".

The first experimental laboratory in psychology was founded in Leipzig (Germany), where Wilhelm Wundt mainly investigated feelings and sensations by employing experimental methods. Almost a century and half after is debut, experimental laboratories have extremely evolved in terms of apparatus, instruments, and recording techniques. Under a multiand interdisciplinary perspective, we can now better understand human cognitive and affective processes. As current zeitgeist has placed increasing emphasis upon the ecologically valid research, an "out-of-thelab" approach, integrated with both human and nonhuman research, is expected to leverage scientific advances in the field of human behavior.

El primer laboratorio experimental de psicología se fundó en Leipzig (Alemania), donde Wilhelm Wundt investigó principalmente los sentimientos y las sensaciones empleando métodos experimentales. Casi siglo y medio después de su debut, los laboratorios experimentales han evolucionado enormemente en cuanto a aparatos, instrumentos y técnicas de registro. Bajo una perspectiva multi e interdisciplinar, ahora podemos comprender mejor los procesos cognitivos y afectivos humanos. Dado que el zeitgeist actual ha puesto cada vez más énfasis en la investigación válida ecológicamente, se espera que un enfoque "fuera del laboratorio", integrado con la investigación humana y no humana, impulse los avances científicos en el campo del comportamiento humano.

What over 1,000,000 participants tell us about online research protocols.

With the ever-increasing adoption of tools for online research, for the first time we have visibility on macro-level trends in research that were previously unattainable. However, until now this data has been siloed within company databases and unavailable to researchers. Between them, the online study creation and hosting tool Gorilla Experiment Builder and the recruitment platform Prolific hold metadata gleaned from millions of participants and over half a million studies. We analyzed a subset of this data (over 1 million participants and half a million studies) to reveal critical information about the current state of the online research landscape that researchers can use to inform their own study planning and execution. We analyzed this data to discover basic benchmarking statistics about online research that all researchers conducting their work online may be interested to know. In doing so, we identified insights related to: the typical study length, average completion rates within studies, the most frequent sample sizes, the most popular participant filters, and gross participant activity levels. We present this data in the hope that it can be used to inform research choices going forward and provide a snapshot of the current state of online research.

PyGellermann: a Python tool to generate pseudorandom series for human and non-human animal behavioural experiments.

OBJECTIVE: Researchers in animal cognition, psychophysics, and experimental psychology need to randomise the presentation order of trials in experimental sessions. In many paradigms, for each trial, one of two responses can be correct, and the trials need to be ordered such that the participant's responses are a fair assessment of their performance. Specifically, in some cases, especially for low numbers of trials, randomised trial orders need to be excluded if they contain simple patterns which a participant could accidentally match and so succeed at the task without learning. RESULTS: We present and distribute a simple Python software package and tool to produce pseudorandom sequences following the Gellermann series. This series has been proposed to pre-empt simple heuristics and avoid inflated performance rates via false positive responses. Our tool allows users to choose the sequence length and outputs a .csv file with newly and randomly generated sequences. This allows behavioural researchers to produce, in a few seconds, a pseudorandom sequence for their specific experiment. PyGellermann is available at https://github.com/YannickJadoul/PyGellermann .

Subliminal attentional bias modification training for itch.

Introduction: Itch is unpleasant and induces the urge to scratch. This is adaptive to remove the itch-inducing stimulus from the skin. Accordingly, itch draws attention to protect our bodily integrity. Recent studies investigated whether attention is preferentially drawn towards its location, i.e., attentional bias (AB), and also whether this bias could be changed in healthy individuals. So far, results are mixed concerning the existance of an attentional bias towards itch stimuli in healthy individuals as well as the impact of modifications. However, available studies have typically focused on conscious processing and might miss preconscious aspects of attention and potential biases at these stages. Methods: This study included 117 healthy individuals who underwent a subliminal Attentional Bias Modification (ABM)- training for itch based on a dot-probe paradigm with itch- related pictures. Participants were randomly assigned to a training towards itch group, a training away from itch group and a control group. This was done by manipulating the itch-target congruency of the dot-probe task during a training block. Pre- and post-training assessments were regular dot-probe tasks. Exploratorily, also attentional inhibition, cognitive flexibility and itch-related cognitions were assessed. Lastly, participants received an itchy stimulus on the inner forearm before and after the ABM-training to assess potential effects on itch sensitivity. Results: Results showed no AB towards itch across groups at baseline, i.e., pre-training, but an AB away from itch, hence, avoidance of itch, post-training. Further analyses showed that this effect was driven by an attentional bias away from itch in the control group, while there were no significant effects in the experimental groups. There was no effect on itch sensitivity. Conclusion: These findings are in line with recent studies on conscious ABM-training for itch and pain that also did not find significant training effects. Therefore, it is suggested that the field of AB might need to reconsider the current assessment of AB. Moreover, AB is probably a dynamic process that is highly dependent on current itch-related goals and relevance of itch in a specific situation. This suggests that processes probably differ in patients with chronic itch and that also ABM-training might work differently in these populations. Clinical trial registration: https://trialsearch.who.int/Trial2.aspx?TrialID=NTR7561, identifier NTR7561.

Gambling on an empty stomach: Hunger modulates preferences for learned but not described risks.

INTRODUCTION: We assess risks differently when they are explicitly described, compared to when we learn directly from experience, suggesting dissociable decision-making systems. Our needs, such as hunger, could globally affect our risk preferences, but do they affect described and learned risks equally? On one hand, decision-making from descriptions is often considered flexible and context sensitive, and might therefore be modulated by metabolic needs. On the other hand, preferences learned through reinforcement might be more strongly coupled to biological drives. METHOD: Thirty-two healthy participants (females: 20, mean age: 25.6 ± 6.5 years) with a normal weight (Body Mass Index: 22.9 ± 3.2 kg/m2 ) were tested in a within-subjects counterbalanced, randomized crossover design for the effects of hunger on two separate risk-taking tasks. We asked participants to choose between two options with different risks to obtain monetary outcomes. In one task, the outcome probabilities were described numerically, whereas in a second task, they were learned. RESULT: In agreement with previous studies, we found that rewarding contexts induced risk-aversion when risks were explicitly described (F1,31  = 55.01, p < .0001, ηp 2  = .64), but risk-seeking when they were learned through experience (F1,31  = 10.28, p < .003, ηp 2  = .25). Crucially, hunger attenuated these contextual biases, but only for learned risks (F1,31  = 8.38, p < .007, ηp 2  = .21). CONCLUSION: The results suggest that our metabolic state determines risk-taking biases when we lack explicit descriptions.

Same same but different: Subtle but consequential differences between two measures to linearly integrate speed and accuracy (LISAS vs. BIS).

Condition-specific speed-accuracy trade-offs (SATs) are a pervasive issue in experimental psychology, because they sometimes render impossible an unambiguous interpretation of experimental effects on either mean response times (mean RT) or percentage of correct responses (PC). For between-participants designs, we have recently validated a measure (Balanced Integration Score, BIS) that integrates standardized mean RT and standardized PC and thereby controls for cross-group variation in SAT. Another related measure (Linear Integrated Speed-Accuracy Score, LISAS) did not fulfill this specific purpose in our previous simulation study. Given the widespread and seemingly interchangeable use of the two measures, we here illustrate the crucial differences between LISAS and BIS related to their respective choice of standardization variance. We also disconfirm the recently articulated hypothesis that the differences in the behavior of the two combined performance measures observed in our previous simulation study were due to our choice of a between-participants design and we demonstrate why a previous attempt to validate BIS (and LISAS) for within-participants designs has failed, pointing out several consequential issues in the respective simulations and analyses. In sum, the present study clarifies the differences between LISAS and BIS, demonstrates that the choice of the variance used for standardization is crucial, provides further guidance on the calculation and use of BIS, and refutes the claim that BIS is not useful for attenuating condition-specific SATs in within-participants designs.

Attention and Free Will in Experimental Psychology: An Unexpected Analysis of Voluntary Action by William James and Theodule Ribot.

This article aims to highlight the difficulties encountered by the experimental psychology promoted by Ribot, at the end of the nineteenth century up until the beginning of the twentieth century, with regard to the question of free will as part of his analysis of voluntary attention. It also aims to shed some light on William James's possible role in Ribot's subtle change of opinion in regards to the power of attention, as a mental effort somehow revealing the possibility of a top-down voluntary activity. In most of Ribot's work, at first glance, the will is understood as a determined product of our idiosyncratic character, of our affective and physiological tendencies-rather than as an autonomous faculty of self-determination. But what might look like Ribot's commitment to determinism calls for some nuance. Some uses of the term "voluntary" in his work, particularly to describe the phenomenon of attention, seem to refer to a form of free will looking a lot more like an autonomous faculty than like a mere illusion induced by an epiphenomenal conscious state. We end the paper with remarks about the current state of studies of consciousness and voluntary action in relation to Ribot and James's accounts of attention and will.

Central executive and target selection in visual working memory / Executivo central e seleção de alvos na memória de trabalho visual / Ejecutivo central y selección de estímulos por la memoria de trabajo visual

The goal of this study was to investigate if the selection of external information for storage in visual working memory requires control by the central executive when the categorization of targets is guided by instructions. The design was experimental 3 (concurrent task) x 2 (instruction). Forty-eight university students saw eight colored shapes, four of them surrounded by square outlines. Memory was assessed using a recognition task. Targets varied with instructions: targets were presented within squares in the first block and outside squares in the second block. There were three concurrent tasks: no task, articulatory suppression, and backward counting. Performance was measured by hits, false alarms, corrected recognition, and sensitivity (A'), compared using within-subject ANOVAs. Results showed a main effect only for concurrent task, with lower performance in the backward counting condition for all measures. These results suggest that the central executive does not control the perceptual filter, corroborating earlier results. (AU)

O objetivo deste estudo foi investigar se a seleção de informações externas para manutenção na memória de trabalho visual requer controle do executivo central, quando a categorização de alvos depende de instrução. O delineamento foi experimental três (tarefa concorrente) x duas (instrução). Participaram 48 universitários. Os participantes viam oito formas coloridas, quatro delas dentro de quadrados. A memória foi avaliada por reconhecimento. Os alvos dependiam de instrução: no primeiro bloco estavam dentro de quadrados e no segundo, fora de quadrados. Havia três tarefas concorrentes: sem tarefa, supressão articulatória e contagem inversa. O desempenho foi avaliado por acertos, alarmes falsos, taxa de reconhecimento correto e índice de sensibilidade A', comparados por meio de ANOVAs intrassujeitos. Os resultados mostraram apenas efeito principal da tarefa concorrente, com menor desempenho na condição contagem inversa em todas as medidas. Esse resultado sugere que o executivo central não controla o filtro perceptual, corroborando resultados anteriores. (AU)

El objetivo fue investigar si la selección de información externa para el mantenimiento de la memoria de trabajo visual requiere un control del ejecutivo central, cuando la categorización de los estímulos depende de instrucciones. El diseño fue experimental 3 (tarea concurrente) x 2 (instrucción). Los 48 estudiantes universitarios participantes vieron ocho formas de colores, cuatro de ellas dentro de cuadrados. La memoria se evaluó por reconocimiento. Los estímulos dependían de la instrucción: en el primer bloque estaban dentro de los cuadrados, y en el segundo, fuera de ellos. Hubo tres tareas recurrentes: ninguna tarea, supresión articulatoria y conteo inverso. El rendimiento se evaluó mediante aciertos, falsas alarmas, tasa de reconocimiento correcto e índice de sensibilidad A', mediante ANOVAs intrasujeto Los resultados mostraron solo el efecto principal de la tarea concurrente, con menor rendimiento en la condición de conteo inverso en todas las medidas. Los resultados sugieren que el ejecutivo central no controla el filtro perceptual, corroborando resultados anteriores. (AU)

Doing Experimental Psychological Research from Remote: How Alerting Differently Impacts Online vs. Lab Setting.

Due to pandemic-imposed restrictions on lab-based research, we have recently witnessed a flourishing of online studies in experimental psychology, based on the collection of fine behavioral measures such as reaction times (RTs) and accuracy. However, it remains unclear whether participants' alerting levels may have a different impact on behavioral performance in the online vs. lab setting. In this work we administered online and in-lab the dynamic temporal prediction (DTP) task, which requires an implicit modulation of participants' alerting by alternating experimental conditions implying either slower or faster response rates. We then compared data distribution, RTs, accuracy, and time-on-task effects across the adult lifespan between the settings. We replicated online and across the whole age range considered (19-69 y) all the task-specific effects already found in-lab (both in terms of RTs and accuracy) beyond the overall RTs delay typical of the online setting. Moreover, we found an interaction between the setting and task-specific features so that participants showed slower RTs only in experimental conditions implying a less urgent response rate, while no RTs delay and a slight accuracy increase emerged in faster conditions. Thus, the online setting has been shown to be methodologically sound in eliciting comparable effects to those found in-lab. Moreover, behavioral performance seems to be more sensitive to task-induced alerting shifts in the online as compared to the lab setting, leading to either a heightened or reduced efficiency depending on a faster or slower response rate of experimental conditions, respectively.

Among-individual differences in auditory and physical cognitive abilities in zebra finches.

Among-individual variation in performance on cognitive tasks is ubiquitous across species that have been examined, and understanding the evolution of cognitive abilities requires investigating among-individual variation because natural selection acts on individual differences. However, relatively little is known about the extent to which individual differences in cognition are determined by domain-specific compared with domain-general cognitive abilities. We examined individual differences in learning speed of zebra finches across seven different tasks to determine the extent of domain-specific versus domain-general learning abilities, as well as the relationship between learning speed and learning generalization. Thirty-two zebra finches completed a foraging board experiment that included visual and structural discriminations, and then these same birds went through an acoustic operant discrimination experiment that required discriminating between different natural categories of acoustic stimuli. We found evidence of domain-general learning abilities as birds' relative performance on the seven learning tasks was weakly repeatable and a principal components analysis found a first principal component that explained 36% of the variance in performance across tasks with all tasks loading unidirectionally on this component. However, the few significant correlations between tasks and high repeatability within each experiment suggest the potential for domain-specific abilities. Learning speed did not influence an individual's ability to generalize learning. These results suggest that zebra finch performance across visual, structural, and auditory learning relies upon some common mechanism; some might call this evidence of "general intelligence"(g), but it is also possible that this finding is due to other noncognitive mechanisms such as motivation.

Toward an Attentive Robotic Architecture: Learning-Based Mutual Gaze Estimation in Human-Robot Interaction.

Social robotics is an emerging field that is expected to grow rapidly in the near future. In fact, it is increasingly more frequent to have robots that operate in close proximity with humans or even collaborate with them in joint tasks. In this context, the investigation of how to endow a humanoid robot with social behavioral skills typical of human-human interactions is still an open problem. Among the countless social cues needed to establish a natural social attunement, this article reports our research toward the implementation of a mechanism for estimating the gaze direction, focusing in particular on mutual gaze as a fundamental social cue in face-to-face interactions. We propose a learning-based framework to automatically detect eye contact events in online interactions with human partners. The proposed solution achieved high performance both in silico and in experimental scenarios. Our work is expected to be the first step toward an attentive architecture able to endorse scenarios in which the robots are perceived as social partners.