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In the Michotte task, a ball (X) moves toward a resting ball (Y). In the moment of contact, X stops und Y starts moving. Previous studies have shown that subjects tend to view X as the causal agent ('X launches Y') rather than Y ('Y stops X'). Moreover, X tends to be attributed more force than Y (force asymmetry), which contradicts the laws of Newtonian mechanics. Recent theories of force asymmetry try to explain these findings as the result of an asymmetrical identification with either the (stronger) agent or the (weaker) patient of the causal interaction. We directly tested this assumption by manipulating attributions of causal agency while holding the properties of the causal interaction constant across conditions. In contrast to previous accounts, we found that force judgments stayed invariant across conditions in which assignments of causal agency shifted from X to Y and that even those subjects who chose Y as the causal agent gave invariantly higher force ratings to X. These results suggest that causal agency and the perception of force are conceptually independent of each other. Different possible explanations are discussed. (PsycINFO Database Record (c) 2016 APA, all rights reserved)
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The goal of the present set of studies is to explore the boundary conditions of category transfer in causal learning. Previous research has shown that people are capable of inducing categories based on causal learning input, and they often transfer these categories to new causal learning tasks. However, occasionally learners abandon the learned categories and induce new ones. Whereas previously it has been argued that transfer is only observed with essentialist categories in which the hidden properties are causally relevant for the target effect in the transfer relation, we here propose an alternative explanation, the unbroken mechanism hypothesis. This hypothesis claims that categories are transferred from a previously learned causal relation to a new causal relation when learners assume a causal mechanism linking the two relations that is continuous and unbroken. The findings of two causal learning experiments support the unbroken mechanism hypothesis. (PsycINFO Database Record (c) 2016 APA, all rights reserved)
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The philosopher David Hume's conclusion that causal induction is solely based on observed associations still presents a puzzle to psychology. If we only acquired knowledge about statistical covariations between observed events without accessing deeper information about causality, we would be unable to understand the differences between causal and spurious relations, between prediction and diagnosis, and between observational and interventional inferences. All these distinctions require a deep understanding of causality that goes beyond the information given. We report a number of recent studies that demonstrate that people and rats do not stick to the superficial level of event covariations but reason and learn on the basis of deeper causal representations. Causal-model theory provides a unified account of this remarkable competence. [ABSTRACT FROM AUTHOR]
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This chapter argues for several interconnected theses. First, the fundamental way that people represent causal knowledge is qualitative in terms of causal structure. Second, people use a variety of cues to infer structure aside from statistical data (e.g., temporal order, intervention, coherence with prior knowledge). Third, once a structural model is hypothesized, subsequent statistical data are used to confirm or refute the model and (possibly) to parameterize it. The structure of a posited model influences how the statistical data are processed. Fourth, people are limited in the number and complexity of causal models that they can hold in mind to test, but they can separately learn and then integrate simple models and revise models by adding and removing single links. Finally, current computational models of learning need further development before they can be applied to human learning. What is needed is a heuristic-based model that shares the strengths and weaknesses of a human learner and can take advantage of the rich causal information that the natural environment provides. (PsycINFO Database Record (c) 2016 APA, all rights reserved)
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The capacity to evaluate causal relations is fundamental to human cognition, and yet little is known of its neurocognitive underpinnings. A functional magnetic resonance imaging study was performed to investigate an hypothesized dissociation between the use of semantic knowledge to evaluate specifically causal relations in contrast to general associative relations. Identical pairs of words were judged for causal or associative relations in different blocks of trials. Causal judgments, beyond associative judgments, generated distinct activation in left dorsolateral prefrontal cortex and right precuneus. These findings indicate that the evaluation of causal relations in semantic memory involves additional neural mechanisms relative to those required to evaluate associative relations. [ABSTRACT FROM AUTHOR]
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Currently, two frameworks of causal reasoning compete: Whereas dependency theories focus on dependencies between causes and effects, dispositional theories model causation as an interaction between agents and patients endowed with intrinsic dispositions. One important finding providing a bridge between these two frameworks is that failures of causes to generate their effects tend to be differentially attributed to agents and patients regardless of their location on either the cause or the effect side. To model different types of error attribution, we augmented a causal Bayes net model with separate error sources for causes and effects. In several experiments, we tested this new model using the size of Markov violations as the empirical indicator of differential assumptions about the sources of error. As predicted by the model, the size of Markov violations was influenced by the location of the agents and was moderated by the causal structure and the type of causal variables. (PsycINFO Database Record (c) 2016 APA, all rights reserved)
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Most studies investigating semantic memory have focused on taxonomic or associative relations. Little is known about how other relations, such as causal relations, are represented and accessed. In three experiments, we presented participants with pairs of words one after another, describing events that referred to either a cause (e.g., spark) or an effect (e.g., fire). We manipulated the temporal order of word presentation and the question participants had to respond to. The results revealed that questions referring to the existence of a causal relation are answered faster when the first word refers to a cause and the second word refers to its effect than vice versa. However, no such asymmetry was observed with questions referring to the associative relation. People appear to distinguish the roles of cause and effect when queried specifically about a causal relation, but not when the same information is evaluated for the presence of an associative relation. (PsycINFO Database Record (c) 2016 APA, all rights reserved)
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The article reviews the book ``Moral Minds: How Nature Designed Our Universal Sense of Right and Wrong,'' by Marc D. Hauser.
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Presents a Bayesian network model to explain causal learning. Its key feature is the decoupling between the temporal order of incoming information and the represented temporal order of events. The 4 steps of the model are (1) setting up an initial causal model, (2) estimating the causal power of each cause, (3) integrating causal power estimates, and (4) subsequent reviews of the causal model. Empirical evidence on estimating causal power is reported, and the model is used to explain asymmetries in cue competition and base-rate use as well as differences in learning linearly separable vs nonlinearly separable category structures. It is concluded that causal models effectively reduce the potential computational complexity of causal learning tasks.
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An efficient auditory system contributes to cognitive and psychosocial development. A right ear advantage in hearing thresholds (HTs) has been described in adults and atypical patterns of left/right hearing threshold asymmetry (HTA) have been described for psychiatric and neurodevelopmental conditions. Previous genome-wide association studies (GWASs) on HT have mainly been conducted in elderly participants whose hearing is more likely to be affected by external environmental factors. Here, we investigated HT and HTA in a children population cohort (ALSPAC, n = 6,743). Better hearing was associated with better cognitive performance and higher socioeconomic status. At the group level, HTA suggested a left ear advantage (mean = -0.28 dB) that was mainly driven by females. SNP heritability for HT and HTA was 0.13 and 0.02, respectively (n = 4,989). We found a modest negative genetic correlation between HT and reading ability. GWAS for HT (n = 5,344) did not yield significant hits but polygenic risk scores for higher educational attainment (EA, ß = -1,564.72, p = .008) and schizophrenia (ß = -241.14, p = .004) were associated with lower HT, that is, better hearing. In summary, we report new data supporting associations between hearing measures and cognitive abilities at the behavioral level. Genetic analysis suggests shared biological pathways between cognitive and sensory systems and provides evidence for a positive outcome of genetic risk for schizophrenia.
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Alterations in functional brain lateralization, often indicated by an increased prevalence of left- and/or mixed-handedness, have been demonstrated in several psychiatric and neurodevelopmental disorders like schizophrenia or autism spectrum disorder. For depression, however, this relationship is largely unclear. While a few studies found evidence that handedness and depression are associated, both the effect size and the direction of this association remain elusive. Here, we collected data from 87 studies totaling 35,501 individuals to provide a precise estimate of differences in left-, mixed- and non-right-handedness between depressed and healthy samples and computed odds ratios (ORs) between these groups. Here, an OR > 1 signifies higher rates of atypical handedness in depressed compared to healthy samples. We found no differences in left- (OR = 1.04, 95% CI = [0.95, 1.15], p = .384), mixed- (OR = 1.64, 95% CI = [0.98, 2.74], p = .060) or non-right-handedness (OR = 1.05, 95% CI = [0.96, 1.15], p = .309) between the two groups. We could thus find no link between handedness and depression on the meta-analytical level.
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Background Alterations in the hippocampus and prefrontal cortex (PFC) have frequently been reported in depressed patients. These parameters might prove to be a consistent finding in depression. In addition, peripheral DNA methylation of the MORC1 gene promoter showed stable associations with depression across independent samples. However, the question arises whether MORC1, supposedly acting as transcription factor, might also be involved in neurobiological alterations accompanying depression. This study further analyses the role of MORC1 in depression by investigating a potential correlation between peripheral MORC1 DNA methylation and neuronal structural properties previously associated with depression in humans. Methods Beck Depression Inventory (BDI) was assessed in 52 healthy participants. DNA was extracted from buccal cells and MORC1 methylation correlated with micro- and macrostructural properties derived from magnetic resonance imaging (MRI) and neurite orientation dispersion and density imaging (NODDI) in the hippocampus and medial prefrontal cortex (mPFC). Results MORC1 methylation was associated with volume reduction and neurite orientation dispersion and density markers in the hippocampus and mPFC. BDI was positively associated with neurite orientation dispersion and density markers in the hippocampus. Limitations The study was conducted in a small sample of healthy participants with subclinical depressive symptoms. Peripheral tissue was analyzed. Conclusion We found significant negative associations between peripheral MORC1 methylation and macro- and microstructural markers in the hippocampus and mPFC. Thus, MORC1 might be involved in neurobiological properties. Studies investigating neuronal methylation patterns of MORC1 are needed to support this hypothesis.
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Human lateral preferences, such as handedness and footedness, have interested researchers for decades due to their pronounced asymmetries at the population level. While there are good estimates on the prevalence of handedness in the population, there is no large-scale estimation on the prevalence of footedness. Furthermore, the relationship between footedness and handedness still remains elusive. Here, we conducted meta-analyses with four diferent classifcation systems for footedness on 145,135 individuals across 164 studies including new data from the ALSPAC cohort. The study aimed to determine a reliable point estimate of footedness, to study the association between footedness and handedness, and to investigate moderating factors infuencing footedness. We showed that the prevalence of atypical footedness ranges between 12.10% using the most conservative criterion of left-footedness to 23.7% including all left- and mixed-footers as a single nonright category. As many as 60.1% of left-handers were left-footed whereas only 3.2% of right-handers were left-footed. Males were 4.1% more often non-right-footed compared to females. Individuals with psychiatric and neurodevelopmental disorders exhibited a higher prevalence of non-right-footedness. Furthermore, the presence of mixed-footedness was higher in children compared to adults and leftfootedness was increased in athletes compared to the general population. Finally, we showed that footedness is only marginally infuenced by cultural and social factors, which play a crucial role in the determination of handedness. Overall, this study provides new and useful reference data for laterality research. Furthermore, the data suggest that footedness is a valuable phenotype for the study of lateral motor biases, its underlying genetics and neurodevelopment.
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Human language is dominantly processed in the left cerebral hemisphere in most of the population. While several studies have suggested that there are higher rates of atypical right-hemispheric language lateralization in left-/mixed-handers, an accurate estimate of this association from a large sample is still missing. In this study, we comprised data from 1,554 individuals sampled in three previous studies in which language lateralization measured via dichotic listening, handedness and footedness were assessed. Overall, we found a right ear advantage indicating typical left-hemispheric language lateralization in 82.1% of the participants. While we found signifcantly more left-handed individuals with atypical language lateralization on the categorical level, we only detected a very weak positive correlation between dichotic listening lateralization quotients (LQs) and handedness LQs using continuous measures. Here, only 0.4% of the variance in language lateralization were explained by handedness. We complemented these analyses with Bayesian statistics and found no evidence in favor of the hypothesis that language lateralization and handedness are related. Footedness LQs were not correlated with dichotic listening LQs, but individuals with atypical language lateralization also exhibited higher rates of atypical footedness on the categorical level. We also found diferences in the extent of language lateralization between males and females with males exhibiting higher dichotic listening LQs indicating more left-hemispheric language processing. Overall, these fndings indicate that the direct associations between language lateralization and motor asymmetries are much weaker than previously assumed with Bayesian correlation analyses even suggesting that they do not exist at all. Furthermore, sex diferences seem to be present in language lateralization when the power of the study is adequate suggesting that endocrinological processes might infuence this phenotype.
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In human social interaction, affective touch plays an integral role to communicate intentions and emotions. Three of the most important forms of social touch are embracing, cradling and kissing. These behaviours have been demonstrated to be lateralized, but the underlying mechanisms are still not well understood. Both motor and emotive biases have been suggested to affect laterality of social touch. We aimed to systematically investigate how motor preferences and emotive biases influence the lateralization of embracing, cradling and kissing within the same sample. Participants performed all three forms of social touch in neutral, positive and negative emotional conditions. Like a previous study, we found a rightward bias for embracing that was modulated by both motor preferences and the emotional content of the situation. Kissing and cradling were not influenced by motor preferences. In general, a negative emotional connotation of the situation led to a reduction of lateral biases in social touch, independent of the individual direction.
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Across time and place, right hand preference has been the norm, but what is the precise prevalence of left- and right-handedness? Frequency of left-handedness has shaped and underpinned different fields of research, from cognitive neuroscience to human evolution, but reliable distributional estimates are still lacking. While hundreds of empirical studies have assessed handedness, a large-scale, comprehensive review of the prevalence of handedness and the factors that moderate it, is currently missing. Here, we report 5 meta-analyses on hand preference for different manual tasks and show that left-handedness prevalence lies between 9.3% (using the most stringent criterion of left-handedness) to 18.1% (using the most lenient criterion of nonright-handedness), with the best overall estimate being 10.6% (10.4% when excluding studies assessing elite athletes’ handedness). Handedness variability depends on (a) study characteristics, namely year of publication and ways to measure and classify handedness, and (b) participant characteristics, namely sex and ancestry. Our analysis identifies the role of moderators that require taking into account in future studies on handedness and hemispheric asymmetries. We argue that the same evolutionary mechanisms should apply across geographical regions to maintain the roughly 1:10 ratio, while cultural factors, such as pressure against left-hand use, moderate the magnitude of the prevalence of left-handedness. Although handedness appears as a straightforward trait, there is no universal agreement on how to assess it. Therefore, we urge researchers to fully report study and participant characteristics as well as the detailed procedure by which handedness was assessed and make raw data publicly available.
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The Edinburgh Handedness Inventory (EHI) and the Waterloo Footedness Questionnaire (WFQ) are two of the most widely used questionnaires to assess lateralized everyday behavior in human participants. However, it is unclear to what extent the specific behavior assessed in these questionnaires elicit lateralized neural activity when performed in real-life situations. To illuminate this unresolved issue, we assessed EEG alpha and beta asymmetries during real-life performance of the behaviors assessed in the EHI and WFQ using a mobile EEG system. This methodology provides high ecological validity for studying neural correlates of motor behavior under more naturalistic conditions. Our results indicate that behavioral performance of items of both the EHI and WFQ differentiate between left- and right-handers and left- and right-footers on the neural level, especially in the alpha frequency band. These results were unaffected by movement parameters. Furthermore, we could demonstrate that neural activity elicited specifically during left-sided task performance provides predictive power for the EHI or WFQ score of the participants. Overall, our results show that these prominent questionnaires not only distinguish between different motor preferences on the behavioral level, but also on the neurophysiological level. Furthermore, we could show that mobile EEG systems are a powerful tool to investigate motor asymmetries in ecologically valid situations outside of the laboratory setting. Future research should focus on other lateralized behavioral phenotypes in real-life settings to provide more insights into lateralized motor functions.
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Schizophrenia patients have a higher probability of altered structural and functional differences between the left and right hemisphere. Schizotypy as its nonclinical manifestation has been related to a higher incidence of non-right-handedness and atypical right-hemispheric language dominance. It has been suggested that genes involved in cilia function might link brain asymmetry and neurodevelopmental disorders. We assessed DNA methylation in the promoter regions of seven candidate genes involved in cilia function and psychiatric disorders from buccal cells and investigated their association with schizotypy and language lateralization in 60 healthy adults. Moreover, we determined microstructural properties of the planum temporale in a subsample of 52 subjects using neurite orientation dispersion and density imaging (NODDI). We found a significant association between schizotypy and DNA methylation in the AHI1 promoter region. Moreover, AHI1 DNA methylation significantly predicted language lateralization and asymmetry in estimated planum temporale neurite density. Finally, stronger leftward asymmetry in estimated neurite density was associated with a more pronounced right ear advantage (left hemisphere dominance) in the forced-right condition of the dichotic listening task, measuring attentional modulation of language lateralization. Our results are in line with a shared molecular basis of schizotypy and functional hemispheric asymmetries that is based on cilia function.
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The earliest form of social contact for a newborn is being cradled by its mother. This important behavior has been found to be lateralized to the left side by many, but not all empirical studies. Factors that have been suggested to modulate cradling asymmetry are handedness and sex. However, these factors have not been demonstrated consistently, possibly due to low sample sizes and inconsistent experimental paradigms. To address this issue, we used a meta-analytical approach to (1) quantify the widely reported leftward bias in human cradling and (2) identify moderating factors of the cradling bias such as handedness and sex. Across forty studies, we observed a leftward cradling bias showing that this effect is robust and replicable. Furthermore, we found that left-handers demonstrate a significantly less pronounced leftward bias compared to right-handers and that males are less lateralized compared to females. In conclusion, we could verify that parental handedness and sex contribute to a cradling population bias. Future studies examining genetic factors could illuminate the mechanism supporting a cradling bias.
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Frontal alpha EEG asymmetry, an indirect marker of asymmetries in relative frontal brain activity, are widely used in research on lateralization of emotional processing. While most authors focus on frontal electrode pairs (e.g., F3/F4 or F7/F8), several recent studies have indicated that EEG asymmetries can also be observed outside the frontal lobe and in frequency bands other than alpha. Because the focus of most EEG asymmetry research is on the correlations between asymmetry and other traits, much less is known about the distribution of patterns of asymmetry at the population level. To systematically assess these asymmetries in a representative sample, we determined EEG asymmetries across the head in the alpha, beta, delta and theta frequency bands in 235 healthy adults. We found significant asymmetries in all four frequency bands and across several brain areas, indicating that EEG asymmetries are not limited to frontal alpha. Asymmetries were not modulated by sex. They were modulated by direction of hand preference, with stronger right-handedness predicting greater right (relative to left) alpha power, or greater left (relative to right) activity. Taken together, the present results show that EEG asymmetries other than frontal alpha represent markers of asymmetric brain function that should be explored further.
