Rasmus Bååth

Performance in eyeblink conditioning is age and sex dependent

A growing body of evidence suggests that the cerebellum is involved in both cognition and language. Abnormal cerebellar development may contribute to neurodevelopmental disorders such as attention deficit hyperactivity disorder (ADHD), autism, fetal alcohol syndrome, dyslexia, and specific language impairment. Performance in eyeblink conditioning, which depends on the cerebellum, can potentially be used to clarify the neural mechanisms underlying the cerebellar dysfunction in disorders like these. However, we must first understand how the performance develops in children who do not have a disorder. In this study we assessed the performance in eyeblink conditioning in 42 typically developing children between 6 and 11 years old as well as in 26 adults. Older children produced more conditioned eyeblink responses than younger children and adults produced more than children. In addition, females produced more conditioned eyeblink responses than males among both children and adults. These results highlight the importance of considering the influence of age and sex on the performance when studying eyeblink conditioning as a measure of cerebellar development.

Estimating the distribution of sensorimotor synchronization data : A Bayesian hierarchical modeling approach.

The sensorimotor synchronization paradigm is used when studying the coordination of rhythmic motor responses with a pacing stimulus and is an important paradigm in the study of human timing and time perception. Two measures of performance frequently calculated using sensorimotor synchronization data are the average offset and variability of the stimulus-to-response asynchronies—the offsets between the stimuli and the motor responses. Here it is shown that assuming that asynchronies are normally distributed when estimating these measures can result in considerable underestimation of both the average offset and variability. This is due to a tendency for the distribution of the asynchronies to be bimodal and left skewed when the interstimulus interval is longer than 2 s. It is argued that (1) this asymmetry is the result of the distribution of the asynchronies being a mixture of two types of responses—predictive and reactive—and (2) the main interest in a sensorimotor synchronization study is the predictive responses. A Bayesian hierarchical modeling approach is proposed in which sensorimotor synchronization data are modeled as coming from a right-censored normal distribution that effectively separates the predictive responses from the reactive responses. Evaluation using both simulated data and experimental data from a study by Repp and Doggett (2007) showed that the proposed approach produces more precise estimates of the average offset and variability, with considerably less underestimation.

Human Non-linguistic Vocal Repertoire : Call Types and Their Meaning

Recent research on human nonverbal vocalizations has led to considerable progress in our understanding of vocal communication of emotion. However, in contrast to studies of animal vocalizations, this research has focused mainly on the emotional interpretation of such signals. The repertoire of human nonverbal vocalizations as acoustic types, and the mapping between acoustic and emotional categories, thus remain underexplored. In a cross-linguistic naming task (Experiment 1), verbal categorization of 132 authentic (non-acted) human vocalizations by English-, Swedish- and Russian-speaking participants revealed the same major acoustic types: laugh, cry, scream, moan, and possibly roar and sigh. The association between call type and perceived emotion was systematic but non-redundant: listeners associated every call type with a limited, but in some cases relatively wide, range of emotions. The speed and consistency of naming the call type predicted the speed and consistency of inferring the caller’s emotion, suggesting that acoustic and emotional categorizations are closely related. However, participants preferred to name the call type before naming the emotion. Furthermore, nonverbal categorization of the same stimuli in a triad classification task (Experiment 2) was more compatible with classification by call type than by emotion, indicating the former’s greater perceptual salience. These results suggest that acoustic categorization may precede attribution of emotion, highlighting the need to distinguish between the overt form of nonverbal signals and their interpretation by the perceiver. Both within- and between-call acoustic variation can then be modeled explicitly, bringing research on human nonverbal vocalizations more in line with the work on animal communication.

Subjective rhythmization: A replication and an assessment of two theoretical explanations

Subjective rhythmization is that phenomenon whereby, when one is listening to a monotone metronome sequence, some sounds are experienced as accented. These subjectively accented sounds group the sequence similarly to how the metrical structure of a piece of music groups the beats. Subjective rhythmization was first investigated by Bolton (1894); the present study aims at replicating and extending that work. Consistent with Boltons results, all participants reported hearing accent patterns when listening to monotone sequences; the reported group size of an accent pattern was highly dependent on the tempo of the sequence. A power relation captured well the relation between the reported group size and the sequence interstimulus interval. Further, the mean group size reported in the subjective rhythmization task was found to correlate with the timing performance in a slowtempo tapping task. These results are consistent with the resonance theory explanation of subjective rhythmization (Large, 2008).

Age Effects on Semantic Coherence: Latent Semantic Analysis Applied to Letter Fluency Data

We investigated age-related changes in the semantic distance between successively generated words in two letter fluency tasks differing with respect to demands placed on executive control. The semantic distance was measured by Latent Semantic Analysis (LSA). The results show that older people have a larger semantic distance between successively generated items than young people, and that this effect is particularly pronounced in the more demanding fluency task. Taken together, our findings support the idea that elderly have a less distinct semantic network compared to young people while also demonstrating the feasibility of LSA as a powerful tool for delineating multifaceted aspects of semantic organization inherent in behavioural data from language production tasks.

Using Bayes Factors to Test Hypotheses in Developmental Research

This article discusses the concept of Bayes factors as inferential tools that can serve as an alternative to null hypothesis significance testing in the day-to-day work of developmental researchers. A Bayes factor indicates the degree to which data observed should increase (or decrease) the credibility of one hypothesis in comparison to another. Bayes factor analyses can be used to compare many types of models but are particularly helpful when comparing a point null hypothesis to a directional or nondirectional alternative hypothesis. A key advantage of this approach is that a Bayes factor analysis makes it clear when a set of observed data is more consistent with the null hypothesis than the alternative. Bayes factor alternatives to common tests used by developmental psychologists are available in easy-to-use software. However, we note that analysis using Bayes factors is a less general approach than Bayesian estimation/modeling, and is not the right tool for every research question.

Affective forecasting in an orangutan : predicting the hedonic outcome of novel juice mixes

Abstract Affective forecasting is an ability that allows the prediction of the hedonic outcome of never-before experienced situations, by mentally recombining elements of prior experiences into possible scenarios, and pre-experiencing what these might feel like. It has been hypothesised that this ability is uniquely human. For example, given prior experience with the ingredients, but in the absence of direct experience with the mixture, only humans are said to be able to predict that lemonade tastes better with sugar than without it. Non-human animals, on the other hand, are claimed to be confined to predicting—exclusively and inflexibly—the outcome of previously experienced situations. Relying on gustatory stimuli, we devised a non-verbal method for assessing affective forecasting and tested comparatively one Sumatran orangutan and ten human participants. Administered as binary choices, the test required the participants to mentally construct novel juice blends from familiar ingredients and to make hedonic predictions concerning the ensuing mixes. The orangutan’s performance was within the range of that shown by the humans. Both species made consistent choices that reflected independently measured taste preferences for the stimuli. Statistical models fitted to the data confirmed the predictive accuracy of such a relationship. The orangutan, just like humans, thus seems to have been able to make hedonic predictions concerning never-before experienced events.

Reasons Pro et Contra as a Debiasing Technique in Legal Contexts

Although legal contexts are subject to biased reasoning and decision making, to identify and test debiasing techniques has largely remained an open task. We report on experimentally deploying the technique “giving reasons pro et contra” with professional (N = 239) and lay judges (N = 372) at Swedish municipal courts. Using a mock legal scenario, participants assessed the relevance of an eyewitness’s previous conviction for his credibility. On average, both groups displayed low degrees of bias. We observed a small positive debiasing effect only for professional judges. Strong evidence was obtained for a relation between profession and relevance-assessment: Lay judges seemed to assign a greater importance to the prior conviction than professional judges did. We discuss challenges for future research, calling other research groups to contribute additional samples.

Prototype Effect and the Persuasiveness of Generalizations.

An argument that makes use of a generalization activates the prototype for the category used in the generalization. We conducted two experiments that investigated how the activation of the prototype affects the persuasiveness of the argument. The results of the experiments suggest that the features of the prototype overshadow and partly overwrite the actual facts of the case. The case is, to some extent, judged as if it had the features of the prototype instead of the features it actually has. This prototype effect increases the persuasiveness of the argument in situations where the audience finds the judgment more warranted for the prototype than for the actual case (positive prototype effect), but decreases persuasiveness in situations where the audience finds the judgment less warranted for the prototype than for the actual case (negative prototype effect).

Quantifying Semantic Linguistic Maturity in Children

We propose a method to quantify semantic linguistic maturity (SELMA) based on a high dimensional semantic representation of words created from the co-occurrence of words in a large text corpus. The method was applied to oral narratives from 108 children aged 4;0–12;10. By comparing the SELMA measure with maturity ratings made by human raters we found that SELMA predicted the rating of semantic maturity made by human raters over and above the prediction made using a child’s age and number of words produced. We conclude that the semantic content of narratives changes in a predictable pattern with children’s age and argue that SELMA is a measure quantifying semantic linguistic maturity. The study opens up the possibility of using quantitative measures for studying the development of semantic representation in children’s narratives, and emphasizes the importance of word co-occurrences for understanding the development of meaning.