[Truncated abstract] Atypical handedness is found to be more prevalent in schizophrenia patients than in psychiatric and normal controls, suggesting atypical brain lateralisation, particularly of regions associated with language. This ‘behavioural aberration’ is commonly considered as a marker of disturbed neurodevelopment, which is usually indexed by minor physical abnormalities. A prevailing view in the literature is that the atypical lateralisation of hand preference provides an additional index for the neurodevelopmental hypothesis of schizophrenia. Consistent with this hypothesis, an atypical lateralisation of hand preferences can also be considered as a consequence of environmental agents that might have interfered with early embryonic development. Notwithstanding the above, an atypical lateralisation of hand preferences can occur as a result of genetic factors as well as an interaction between genetic and environmental factors. The overall objective of this thesis was to advance existing knowledge on atypical laterality in schizophrenia by addressing its various (though related) aspects, including measurement, classification and conceptualisation. Atypical lateralisation of hand preferences in schizophrenia patients was approached by five separate studies. ... Overall, this thesis argues that the causes of atypical lateralisation of hand preferences are due to combined genetic and environmental factors and that its use as a marker of vulnerability to schizophrenia is limited. A cautious interpretation of various associations between the laterality and other measures, particularly cognitive measures, is advised until a broad agreement on the true nature of handedness is reached.

The relationship of current manual preference (phenotypic handedness) and family history of handedness (genotypic handedness) to memory for imageable stimuli was studied. The purpose of the study was to test the hypothesis that genotypic handedness was related to lessened cerebral lateralization of Paivio's (1969) dual memory systems. The structure of memory was not at issue, but the mediation of storage and retrieval in memory has been explained with reference to verbal or imaginal processes. Verbal mediation theories and supporting data were reviewed along with imaginal theories and supporting data for these latter theories. Paivio's (1969) dual coding and processing theory was considered a conceptual bridge between the competing positions.

Embodied Cognition accounts propose that motor activation contributes to semantic representations in action language (Fischer & Zwaan, 2008). However, the nature of this activation remains largely unspecified: in particular, which processes result in relevant activation? Long-term motor experience (e.g., the comprehender’s dominant hand), short-term motor experience (e.g., the hand the comprehender has recently used), and action planning (e.g., the hand the comprehender is planning to use) are all potential candidates. This thesis uses a range of psycholinguistic methods (e.g., timed sentence-picture matching, two-alternative forced-choice sentence-picture matching, spoken sensibility judgements) to distinguish between these possibilities. A first set of experiments investigated how comprehenders’ handedness affects their interpretation of sentences describing manual actions (e.g., I am slicing the tomato). Participants matched sentences of actions to pictures of that action. The Body-Specificity Hypothesis (Casasanto, 2009; Willems, Hagoort, & Casasanto, 2010) predicts that right-handed and left-handed comprehenders will interpret manual action sentences differently, according to whether they would perform that action with their right or their left hand. However, we found that comprehenders appear to interpret manual action sentences according to the hand they use to respond to the task, and not the hand they would typically use to perform manual actions. In addition, this effect was stronger for first-person than third-person sentences, implying that the effect of motor activation is moderated by linguistic context. A second set of experiments used the same paradigm but manipulated at what point comprehenders knew which hand they would use to respond to the sentences: during sentence processing, or after sentence processing was complete. We replicated the finding that comprehenders interpret manual action sentences according to their response hand, and that this effect was stronger for first- than for third-person sentences; but only when comprehenders knew their response hand during sentence processing. In both sets of experiments, there was no effect of whether the picture of the action was presented from an egocentric or allocentric perspective, implying that action sentences are encoded for what effector (in this case, hand) will be used in the action, but not necessarily from what perspective the action will occur. A third set of experiments investigated the existence of a causal role of action planning-based activation on sentence processing. Many studies have shown an effect of language processing on action execution (e.g., Glenberg & Kaschak, 2002; Glenberg et al., 2008), but a fully embodied theory of language also predicts an effect of motor activation on language processing. Here, right-handed participants made spoken judgements about sentences while planning an action with their right or left hand that matched or did not match the action described in the sentence. An effect of response hand on accuracy was found when the task required participants to explicitly judge the congruency of sentence and the action they were preparing, but not otherwise. These results corroborate recent research suggesting that activation of embodied lexical representations may be goal-driven rather than an automatic aspect of language processing (Hoedemaker & Gordon, 2013). Overall, the experiments presented in this thesis suggest a possible role for planning-based motor activation in sentence processing, in line with embodied approaches; however, the results challenge strong accounts of embodiment by suggesting that the effect of planning-based activation is not automatic, and is moderated by linguistic context and task demands.

Human manual action exhibits a differential use of a non-dominant (typically, left) and a dominant (typically, right) hand. Human communication exhibits a pervasive structuring of utterances into topic and comment. I will point out striking similarities between the coordination of hands in bimanual actions, and the structuring of utterances in topics and comments. I will also show how principles of bimanual coordination influence the expression of topic/comment structure in sign languages and in gestures accompanying spoken language, and suggest that bimanual coordination might have been a preadaptation of the development of information structure in human communication.

Dissertation (Ph.D.)--University of Toledo, 2009. / Typescript. "Submitted as partial fulfillment of the requirements for the Doctor of Philosophy in Psychology." Bibliography: leaves 58-66.

published_or_final_version / Linguistics / Master / Master of Arts

Investigating the neurophysiology behind our action encoding system offers a way of probing the underlying mechanisms regarding how we understand seen action. The ability to mentally simulate action (motor simulation) is a strong proposal to understand how we interpret others’ actions. The process of how we generate accurate motor simulations is proposed to be reliant on the context of the movement and sensory feedback from the limb. However, the neurophysiological mechanisms behind motor simulation are not yet understood. Known motor physiology for right-handed individuals show there is a left parietal-frontal network for the mental simulation of skilled movements; however, it remains unclear whether this is due to right limb dominance of the observer’s motor system because action simulation research has been focused primarily on right-handed individuals. The goal of this dissertation is to understand the underlying neurophysiology of the motor simulation process during action encoding. Generally, we propose different strategies of action simulation between right and left handed individuals. More specifically, we propose that right-handed individuals rely on their motor dominant left hemisphere for action encoding and motor simulation, while left-handed individuals will rely on their motor dominant right hemisphere. We will test this by evaluating neurobehavioral patterns of potential symmetry and asymmetry of motor simulation and action encoding based on patterns of limb dominance. We will also evaluate how impaired sensory feedback affects motor simulations, which can reveal how limb state affects the simulation process. The results of this series of studies will fill a void in our basic understanding of the motor simulation process and may generalize to populations with upper limb functional loss. Specifically, those with different hand dominance may require different rehabilitation programs in order to retrain an affected limb.

Age-related decline in memory and other cognitive functions, such as visuospatial functions is widely studied and well documented. In recent years, some studies have also found relationships between memory performance and functional body lateralization, with individuals who are inconsistently lateralized (e.g. have inconsistent handedness) scoring higher on episodic memory tests. The objectives of this study were to investigate relationships and possible differences between episodic and semantic memory performance, and visuospatial functions as a function of functional lateralization consistency in a large population-based study. In total, 1283 adult men and women participants, with age ranging from 25 to 100 years, were tested within the Betula prospective cohort study (Nilsson et al., 1997) where they were included in the fifth wave (T5) of data collection. Participants were divided into groups of consistent or inconsistent functional lateralization regarding respective hand-, foot-, and eyedness. Results revealed weak to moderate relationship between variables of functional laterality and its consistency. While age was significant predictor of memory performance and visuospatial functions, sex and functional laterality consistency variables were insignificant. Results are discussed in relation to previous studies and to hemispheric interaction theory. / Betula prospective cohort study (Nilsson et al., 1997, 2004)

A preterm birth is associated with increased risk for neurocognitive deficits, but there is a need to further investigate brain/behavior relations among younger school age children born preterm. The main purpose of this study was to investigate relations between brain volumes and neuropsychological functioning, with an additional aim of examining side preference, among 18 school age children, nine born extremely/very preterm and nine born at-term. Brain volumes were examined using 3T MRI, neuropsychological functioning by WISC-IV and side preference through laterality observations. The children born preterm had, in general lower total brain volume, gray matter and WISC-IV score. Contrary to previous findings no difference was found regarding white matter volumes. Stronger right hand preference was associated to higher perceptual reasoning ability among both preterm and at-term born children, but the associations between right hand preference and brain volumes differed between the groups. The results in this study support previous findings showing long-term neurocognitive effects of a preterm birth.

Issued also as thesis, Columbia Univ. / Bibliography: p. 75-80.