The human motor system is constantly faced with decisions about how to choose a path when navigating our environment. These types of decisions occur rapidly and constantly, from initial movement planning, through movement execution, to completion. With infinite ways to complete any given task, the central nervous system generally, and motor control systems specifically, must somehow “decide” the best way to do this while taking into account physiological and environmental constraints. In addition, these movement choices must consider the feasibility and efficiency of all movement alternatives. For example, when deciding between paths that vary in reach distance and walking distance, the path with the shorter reach distance is more likely to be chosen, as reaching is deemed to be ~10x more costly than walking a given distance (Rosenbaum et al., 2011; Rosenbaum, 2012). It is not clear, however, how much more costly the non-chosen path is, compared to the chosen path, and what factors are mediating these decisions. Thus, the purpose of this thesis was to investigate potential underlying non-cognitive mediators of behavioural decisions involved with posture selection during tasks that occur within a constrained task environment, by quantifying the biomechanical mechanisms that may be driving these decisions. Chapter 2 replicated and extended upon the work of Rosenbaum et al. (2011) by recording whole-body motion capture during a bucket transfer task. This study was the first to look at the loading of the shoulder joint and trunk during the reaching and walking decision paradigm, comparing joint loading in the chosen versus unchosen paths. In Chapter 3, participants made decisions between movements with seemingly similar functional distances, in a four-choice reaching and walking paradigm. Behavioural outcomes suggest that the decision-making process reflects spatial coding of the movement goal that is backwards planned from the task sub-goal. Chapter 4 explored how perceived costs of multiple task variables are prioritized and integrated into action planning. Here, participants prioritized decreased reach distance over bearing an increased load. Collectively, this thesis provides evidence that bottom-up processes, namely the biomechanics of the shoulder and trunk, exert influence on cognitive decision-making and action planning, as reflected in decreased joint loading in chosen versus unchosen paths. / Dissertation / Doctor of Philosophy (PhD)

Human functional laterality, typically involving a right-sided preference in most sensory-motor activities, is still a poorly understood issue. This is perhaps particularly true in terms of what underlying mechanisms that may govern lateral biases, as well as the developmental origins and course of events. The present thesis aims at investigating functional asymmetries in the upper and lower body movements of young human infants. In Study I, the presence of side biases in the stepping and placing responses and head turning in healthy fullterm newborns were explored. No evident lateral bias for the leg responses in terms of the first foot moved or direction of head turning was found. However, a lateral bias was revealed for onset latency in relation to the first foot moved in both stepping and placing. Asymmetries in head turning did not correspond to asymmetries in leg movements. In Study II, functional asymmetries in the stepping response of newborn infants were investigated in more detail by means of 3-D kinematic movement registration. Evident side differences were found in relation to smoother movement trajectories of the right leg by means of less movement segmentation compared to the left leg. Side differences were also found in relation to intralimb coordination in terms of stronger ankle-knee couplings and smaller phase shifts in the right leg than the left. In Study III, using the same movement registration technique, the kinematics of left and right arm movements during goal-directed reaching in infants were prospectively studied over the ages 6, 9, 12, and 36 months. Main findings included side differences and developmental trends related to the segmentation of the reaching movements and the reaching trajectory, as well as the distribution of arm-hand-use frequency. The results from Study I and II are discussed in relation to underlying neural mechanisms for lateral biases in leg movements and the important role of a thorough methodology in investigating newborn responses. Findings from Study III are discussed in terms of what they imply about the developmental origins for hand preference. An emphasis is also put on developmental differences between fullterm and preterm infants. Overall, the studies of the present thesis show that an increased understanding of subtle expressions of early functional asymmetries in the upper and lower body movements of young infants may be gained by means of refined measurements. Furthermore, such knowledge may provide an insight into the underlying neural mechanisms subserving asymmetries in the movements of young infants. The present studies also add new information to the current understanding of the development of human lateralized functions, in particular the findings derived from the longitudinal data. Apart from theoretical implications, the present thesis also involves a discussion with regard to the clinical relevance of investigating functional asymmetries in the movements of young infants.

The diploma Thesis objective is analysis of macroeconomic development of Belarus during years 2000-2011. I've decided to focus on the effects of monetary policy that was executed by the central bank in particular years. The final outcome of the macroeconomic analysis is the evaluation of the success of monetary policy executed by the central bank.

O objetivo deste trabalho é analisar influências do Fit Estratégico para o alcance de acordos em negociações de Fusões e Aquisições (F&A). A metodologia envolveu pesquisa qualitativa com suporte quantitativo para desenvolver estrutura analítica que integrasse elementos de F&A e Negociação, permitindo identificar e avaliar 115 variáveis em 20 casos reais de negociações de F&As, 10 com Acordo Alcançado e 10 com Acordo Não Alcançado. Embora com limitações, o estudo alcançou os objetivos propostos identificando quatro Macrorrelações de Influência (MRI) principais: Existência de Fit Estratégico influencia positivamente a chance de acordo, através das Sinergias, assim como sua ausência influencia negativamente; Riscos e Impedimentos integram a Equação de Valor para o Comprador, quando eles ameaçam a captura de valor, podem inviabilizar a chance de acordo; Pressões Indutoras influenciam positivamente a chance de acordos em operações de F&As; e, Interesses Críticos Convergentes são condição precedente para o alcance de acordos em operações de F&As. Esta dissertação contribui para o desenvolvimento de uma visão integrada entre F&A e Negociação, permitindo uma conduta mais consciente, consistente e estratégica para alcançar acordos. Atenção particular é dada à MRI que envolve Fit Estratégico. Além de demonstrar ser forte fator de influência (82% dos casos com Fit atingiram acordo), a estrutura analítica quantitativa utilizada se revelou robusta (os resultados observados nos 20 casos confirmam estudo anterior com 218 casos de Shelton, 1988), apresentando aptidão para ser convertida em ferramenta de suporte à decisão, já que permite avaliar potencial sinérgico entre empresas e nichos de mercado. / The objective of this work is to analyze the influences of Strategic Fit in order to reach agreements in Mergers and Acquisitions (M&A) negotiations. The method involved a qualitative research with quantitative support to develop an analytical framework that integrates elements of M&A and Negotiation, allowing to identify and evaluate 115 variables in 20 actual cases of M&A negotiations of Which 10 Reached a Deal, and 10 Did Not Reach a Deal. Although with limitations, the study achieved its proposed objectives identifying four macro-relations of influence (MRI): Strategic Fit presence positively influences the chance of an agreement, through Synergies and its absence has a negatively influence; Risks and Impediments are part of the Value Equation to the Buyer, when threatening the capture of value they can prevent the chance of agreement; Inducing Pressures positively influences the chance of agreements in M&A transactions; and Critical Converging Interests is a pre-condition to reach agreements in M&A operations. This dissertation contributes to the development of an integrated view between M&A and Negotiation, enabling a more cognizant, consistent and strategic behavior in order to reach agreements. Particular attention is given to the MRI that involves Strategic Fit, as it proved a strong influencing factor (82% of cases with Strategic Fit reached an agreement). As well, the quantitative analytical framework used showed to be robust (results in the 20 cases studied in here confirmed a previous study by Shelton in 1988 of 218 cases) indicating potential to become a decision-supporting tool, since it allows the synergy potential evaluation between companies and market niches.

To coordinate visual perception and motor control in daily life where we are constantly surrounded by motion, we are dependent on normal visuomotor capacity. One essential prerequisite for normal visuomotor capacity is smooth pursuit eye movements (SP). Infants born very preterm (VPT = born <32 gestational weeks) are at high risk of developing disabilities in higher brain functions i.e. perception, cognition, concentration and coordination. In this thesis visuomotor capacity was investigated in a cohort of VPT infants (n = 113) and compared to control groups of full term (FT) infants. Levels of SP were measured at 2 and 4 months’ corrected age (CA). At 8 months’ CA reaching capacity toward a moving object was evaluated as this represents an executive activity guided by vision that develops at an early age. Lower levels of SP were found in the VPT infants compared to FT controls. The VPT boys showed higher levels of SP compared to the VPT girls. In VPT infants without major neonatal morbidities lower levels of SP was found compared to the FT controls. No difference in total capacity of gaze tracking was found, although the VPT infants lagged the object more at 4 months’ CA and used more saccades at 2 months’ CA. With age the VPT infants’ SP levels increased, but with a wider dispersion compared to the FT controls, and the levels of SP at 4 months’ CA corresponded to the levels of the FT infants at 2 months.  A number of perinatal risk factors were found to be negatively associated to lower levels of SP, and this effect was more pronounced in VPT infants with multiple risk factors,.  When evaluating the capacity to reach a moving object at 8 months’ CA, the VPT infants showed significantly more bimanual reach and more curved reaching paths to catch the object as compared to the FT control group. In conclusion, a delayed visuomotor capacity was found in VPT infants compared to FT control infants at 2, 4 and 8 months’ CA. Some VPT infants with perinatal risk factors did not develop in levels of SP between 2 and 4 months’ CA.

Submitted by Ronildo Prado (ronisp@ufscar.br) on 2017-09-05T19:45:54Z No. of bitstreams: 1 DissNTSS.pdf: 3402830 bytes, checksum: 00ff2b842c3bea94aa14e85bf96cd5fd (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2017-09-05T19:46:07Z (GMT) No. of bitstreams: 1 DissNTSS.pdf: 3402830 bytes, checksum: 00ff2b842c3bea94aa14e85bf96cd5fd (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2017-09-05T19:46:21Z (GMT) No. of bitstreams: 1 DissNTSS.pdf: 3402830 bytes, checksum: 00ff2b842c3bea94aa14e85bf96cd5fd (MD5) / Made available in DSpace on 2017-09-05T19:46:29Z (GMT). No. of bitstreams: 1 DissNTSS.pdf: 3402830 bytes, checksum: 00ff2b842c3bea94aa14e85bf96cd5fd (MD5) Previous issue date: 2017-02-13 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Aims: To identify the level of trunk control and to analyse the influence of sitting posture in a ring and seated with flexion at 90º in infants born late preterm infants with corrected age, and at term between 6 and 8 months with the support manual exact of trunk during reaching. Methods: A longitudinal study was performed with 36 full- term infants and 20 infants born preterm infants at 6-8 months of corrected age. The infants were submitted to three evaluations monthly: 1) Segmental Assessment of Trunk Control (SATCo), to identify the exact level of trunk control of infants; 2) assesssment of reaching movement, using kinematics; And 3) Alberta Infant Motor Scale (AIMS) to assess motor control of infants and to ensure the minimum 25th percentile for full-term infants. For the kinematic analysis, the infants were placed on a table in the sitting posture in a ring and seated with flexion at 90º of hip, knee and ankle. All infants during the reaching analysis received the exact and necessary manual support in the trunk according to the control level of each infant evaluated through the SATCo. To elicit reaching, an attractive, malleable or rigid object was presented on the midline, 45 ° to the right and 45 ° to the left of the infant's body. The total time of evaluation in each sitting posture was 2 minutes. It was considered variable full reaching frequency on the right, left and midline, and spatio-temporal variables to the right, left and midline (movement unit, straightness index, deceleration index, duration of movement, mean velocity, velocity peak, and trunk displacement. Results: Late preterm infants with corrected age were found to have lower trunk control compared to full-term infants at all ages evaluated. The level of trunk control presented a progressive and descending (cephalo-caudal) order with increasing age in both groups. The reaching frequency was greater at 6 months in the seated ring posture and at 7 and 8 months in the seated posture with 90 ° flexion in both groups. The sitting posture in a ring and with 90 ° flexion did not influence the kinematic variables, except for the right and midline velocity peak, and the trunk displacement to the right. On the other hand, significant differences between group and time were observed. The preterm group presented a higher number of movement units, lower, straightness index, higher average velocity and peak velocity, and lower trunk displacement in comparison to infants full term. In both groups, the spatio-temporal reaching variables improved over time, that is, older infants (8 months) presented lower number of movement units and higher straightness índex compared to younger infants (6 months). Conclusion: Late preterm infants had lower levels of trunk control compared to full-term infants. The postures seated in a ring and seated with 90 ° flexion did not influence the reaching behavior in the late term and preterm infants, since, the exact and necessary manual support was provided in the trunk of the infants, according to the level of control, evaluated through of SATCo. Thus, when the infant received the necessary manual trunk support, the different sitting postures did not influence the reaching behavior. Finally, preterm infants with corrected age, had less rectilinear, non-fluid and immature reaches compared to full-term infants at all ages evaluated. Reaches have become more mature over time, especially in full- erm infants. / Objetivo: Identificar o nível de controle de tronco e analisar a influência da postura sentada em anel e sentada em flexão a 90° em lactentes nascidos pré-termo tardios com idade corrigida, e a termo entre 6 e 8 meses de idade com o suporte manual exato de tronco durante o alcance. Métodos: Foi realizado um estudo longitudinal, com 36 lactentes nascidos a termo e 20 lactentes nascidos pré-termo tardios com idade corrigida aos 6-8 meses de idade. Os lactentes foram submetidos a três avaliações mensalmente: 1) Segmental Assessment of Trunk Control (SATCo), para identificar o nível exato de controle de tronco dos lactentes; 2) avaliação do movimento de alcance, por meio da análise cinemática; e 3) Alberta Infant Motor Scale (AIMS) para avaliar o controle motor dos lactentes e assegurar o percentil mínimo de 25 para os lactentes nascidos a termo. Para a análise cinemática, os lactentes foram posicionados em um tablado na postura sentada em anel e sentada com flexão a 90º de quadris, joelhos e tornozelos. Todos os lactentes durante a análise do alcance receberam o suporte manual exato e necessário no tronco de acordo com o nível de controle de cada lactente avaliado por meio da SATCo. Para eliciar o alcance um objeto atrativo, maleável ou rígido foi apresentado na linha média, 45º à direita e 45° à esquerda do corpo do lactente. O tempo total da avaliação em cada postura sentada foi de 2 minutos. Foi considerada variável frequência total de alcance à direita, esquerda e linha média, e as variáveis espaço-temporais à direita, esquerda e linha média (unidade de movimento, índice de retidão, índice de desaceleração, duração do movimento, velocidade média, pico de velocidade, e deslocamento do tronco. Resultados: constatou-se que lactentes pré-termo tardios, com a idade corrigida, apresentaram menor nível de controle de tronco em comparação aos lactentes a termo em todas as idades avaliadas. O nível de controle de tronco apresentou uma ordem progressiva e descendente (céfalo-caudal) com o aumento da idade em ambos os grupos. A frequência de alcance foi maior aos 6 meses na postura sentada em anel e aos 7 e 8 meses na postura sentada com flexão a 90° em ambos os grupos. A postura sentada em anel e flexão a 90° não influenciou as variáveis cinemáticas do alcance, exceto o pico de velocidade à direita e linha média, e o deslocamento do tronco à direita. Por outro lado, observou-se diferenças significativas entre os grupos e tempo. O grupo pré-termo tardio apresentou maior número de unidades de movimento, menor índice de retidão, maior velocidade média e pico de velocidade, e menor deslocamento de tronco em comparação aos lactentes a termo. Em ambos os grupos, as variáveis espaço-temporais do alcance melhoraram com o tempo, ou seja, lactentes mais velhos (8 meses de idade) apresentaram menor número de unidades de movimento e maior índice de retidão em comparação a lactentes mais novos (6 meses de idade). Conclusão: lactentes pré-termo tardios apresentaram menor nível de controle de tronco em comparação aos lactentes a termo. As posturas sentada em anel e sentada com flexão a 90° não influenciaram no comportamento do alcance nos lactentes a termo e pré-termo tardios, uma vez que, foi fornecido o suporte manual exato e necessário no tronco dos lactentes, de acordo com o nível de controle, avaliado por meio SATCo. Desta forma, quando o lactente recebeu o suporte manual de tronco necessário, as diferentes posturas sentadas não influenciaram no comportamento do alcance. Por fim, lactentes pré-termo tardios, com a idade corrigida, apresentaram alcances menos retilíneos, não fluentes e imaturos em comparação aos lactentes a termo em todas as idades avaliadas. Os alcances se tornaram mais maduros ao longo do tempo, principalmente nos lactentes a termo.

Human movements are remarkably adaptive, such that we are capable of completing movements in a novel environment with similar accuracy to those performed in a typical environment. Our ability to perform in these environments involves accurate processing of sensory feedback for online and offline control. These processes of control have been widely studied for well learned actions, but not for actions in a novel visuomotor environment. In two experiments, we examined control processes underlying reaches when participants were first introduced to a visuomotor rotation (Experiment 1) and then following visuomotor adaptation (Experiment 2). All participants completed 150 reach training trials when (1) a cursor accurately represented their hand motion (i.e., aligned cursor) and (2) a cursor was rotated 45 degrees clockwise relative to their hand motion (i.e., rotated cursor). In Experiment 1, we sought to determine if the control processes underlying movements in typical and novel visuomotor conditions were comparable. Participants (n = 16) received either continuous visual feedback or terminal visual feedback regarding movement endpoint during reach training. Analyses revealed that participants were able to demonstrate similar outcomes (i.e., movement time and endpoint errors) regardless of visual or cursor feedback, but also demonstrated more offline control (i.e., took more time planning and were less consistent in initiating their movements) when reaching with a rotated cursor compared to an aligned cursor, even at the end of training. Together, the results suggest a greater contribution of offline control processes and less effective online corrective processes when reaching in a novel environment compared to when reaching in a typical environment. In attempt to promote online corrective processes, participants (n = 16) in Experiment 2 first completed the training trials with continuous visual feedback and then completed an additional 45 reaches under (1) slow movement time (i.e., Slow MT: 800-1000 ms) and (2) fast movement time (i.e., Fast MT: 400-500ms) constraints. Results showed a shift to online control (i.e., greater endpoint accuracy) when reaching with an aligned and rotated cursor, when sufficiently more time was provided (i.e., Slow MT). Specifically, participants were able to more effectively utilize visual feedback for online control under the Slow MT constraint compared to when reaching quickly (i.e., Fast MT). Together, these experiments demonstrate a flexibility in control processes underlying reaches with rotated visual feedback of the hand. In that reaches first engage in offline control processes during adaptation to a visuomotor rotation, and then shift to online corrective processes following visuomotor adaptation.

O objetivo deste trabalho é analisar influências do Fit Estratégico para o alcance de acordos em negociações de Fusões e Aquisições (F&A). A metodologia envolveu pesquisa qualitativa com suporte quantitativo para desenvolver estrutura analítica que integrasse elementos de F&A e Negociação, permitindo identificar e avaliar 115 variáveis em 20 casos reais de negociações de F&As, 10 com Acordo Alcançado e 10 com Acordo Não Alcançado. Embora com limitações, o estudo alcançou os objetivos propostos identificando quatro Macrorrelações de Influência (MRI) principais: Existência de Fit Estratégico influencia positivamente a chance de acordo, através das Sinergias, assim como sua ausência influencia negativamente; Riscos e Impedimentos integram a Equação de Valor para o Comprador, quando eles ameaçam a captura de valor, podem inviabilizar a chance de acordo; Pressões Indutoras influenciam positivamente a chance de acordos em operações de F&As; e, Interesses Críticos Convergentes são condição precedente para o alcance de acordos em operações de F&As. Esta dissertação contribui para o desenvolvimento de uma visão integrada entre F&A e Negociação, permitindo uma conduta mais consciente, consistente e estratégica para alcançar acordos. Atenção particular é dada à MRI que envolve Fit Estratégico. Além de demonstrar ser forte fator de influência (82% dos casos com Fit atingiram acordo), a estrutura analítica quantitativa utilizada se revelou robusta (os resultados observados nos 20 casos confirmam estudo anterior com 218 casos de Shelton, 1988), apresentando aptidão para ser convertida em ferramenta de suporte à decisão, já que permite avaliar potencial sinérgico entre empresas e nichos de mercado. / The objective of this work is to analyze the influences of Strategic Fit in order to reach agreements in Mergers and Acquisitions (M&A) negotiations. The method involved a qualitative research with quantitative support to develop an analytical framework that integrates elements of M&A and Negotiation, allowing to identify and evaluate 115 variables in 20 actual cases of M&A negotiations of Which 10 Reached a Deal, and 10 Did Not Reach a Deal. Although with limitations, the study achieved its proposed objectives identifying four macro-relations of influence (MRI): Strategic Fit presence positively influences the chance of an agreement, through Synergies and its absence has a negatively influence; Risks and Impediments are part of the Value Equation to the Buyer, when threatening the capture of value they can prevent the chance of agreement; Inducing Pressures positively influences the chance of agreements in M&A transactions; and Critical Converging Interests is a pre-condition to reach agreements in M&A operations. This dissertation contributes to the development of an integrated view between M&A and Negotiation, enabling a more cognizant, consistent and strategic behavior in order to reach agreements. Particular attention is given to the MRI that involves Strategic Fit, as it proved a strong influencing factor (82% of cases with Strategic Fit reached an agreement). As well, the quantitative analytical framework used showed to be robust (results in the 20 cases studied in here confirmed a previous study by Shelton in 1988 of 218 cases) indicating potential to become a decision-supporting tool, since it allows the synergy potential evaluation between companies and market niches.

Made available in DSpace on 2016-06-02T20:18:08Z (GMT). No. of bitstreams: 1 TeseRPC.pdf: 1767809 bytes, checksum: ef4d011c683c35c6fe9f5c598125e152 (MD5) Previous issue date: 2007-03-29 / Financiadora de Estudos e Projetos / The aim of the current research was to examine the influence of intrinsic and extrinsic constraints on reaching movements in 4-6-month-old infants. Age, level of skill and experience gained by spontaneous practice of reaching were the intrinsic constraints analyzed. The relationship between muscular torque required for reaching and gravitational torque was the extrinsic constraint, which was manipulated by different body orientations. Kinematical and qualitative variables for movements performed in supine, reclined and seated positions were analyzed in three different studies in order to verify how constraints affect young infants reaching. The results indicate that body orientation affected reaching behavior in 4- month-old infants. However, when considering the level of skill rather than age, body orientation was shown to affect reaching behavior during its emergence only in less-skilled reachers. The level of skill is thus suggested to be a more relevant constraint than age in the acquisition of reaching. Temporal and spatio-temporal parameters of reaching were more sensitive to constraints imposed by body orientation, age and level of skill. Seated position elicited both reaching in less-skilled reachers during the behavior acquisition and grasping in more-skilled reachers after spontaneous practice. These findings suggest that level of skill, experience in reaching, and body orientation may affect reaching behavior in young infants. These constraints should therefore be taken into account when examining the development of infant reaching. This work supports the idea that the confluence of constraints determines the young infants action and that a change in this confluence can eventuate in a change in action. / O objetivo do presente trabalho foi verificar a influência de restrições intrínsecas e extrínsecas no alcance de lactentes de 4 a 6 meses. As restrições intrínsecas consideradas foram idade, nível de habilidade e experiência obtida através da prática espontânea. A relação entre o torque muscular necessário para a realização do alcance e o torque gravitacional foi a restrição extrínseca analisada, a qual foi manipulada através das diferentes orientações corporais. Variáveis cinemáticas e qualitativas dos alcances realizados nas posições supina, reclinada e sentada foram analisadas em três estudos diferentes, com o propósito de verificarmos como as restrições influenciam no alcance de lactentes jovens. Os resultados indicaram que a orientação corporal afetou o comportamento de alcance de lactentes aos 4 meses. No entanto, ao considerarmos o nível de habilidade ao invés da idade, o alcance foi influenciado pelas orientações corporais somente para os lactentes menos habilidosos. Sugerimos que o nível de habilidade é uma restrição mais relevante que idade no período de aquisição do alcance. Os parâmetros temporais e espaço-temporais do alcance mostraram-se mais sensíveis às restrições impostas pelas orientações corporais, idade e níveis de habilidade. A posição sentada favoreceu o alcance para lactentes menos-habilidosos no período de aquisição, e a preensão para os mais-habilidosos após um mês de prática espontânea. Esses achados sugerem que o nível de habilidade, experiência no alcance e diferentes orientações corporais influenciam o alcance de lactentes jovens. Por isso, essas restrições devem ser consideradas nas pesquisas sobre o desenvolvimento do alcance. Esse trabalho suporta a idéia de que a confluência das restrições determina as capacidades de ação de lactentes jovens e que mudanças nessa confluência podem gerar mudanças na ação.

Made available in DSpace on 2016-06-02T20:18:25Z (GMT). No. of bitstreams: 1 TeseNACFR.pdf: 2711571 bytes, checksum: 92270e5216edbb80d0322257785dcd41 (MD5) Previous issue date: 2006-03-10 / Universidade Federal de Sao Carlos / Many studies have shown that object properties can lead to adjustments in reaching, but few have investigated the specific influence of object size and rigidity on reaching movements in young infants, especially by using kinematic analysis. Objective: Investigate the effect of object size and rigidity in the qualitative and quantitative variables of reaching in 4-to-6- month-old infants, and verify how such variables change over age. Methods: Nine healthy infants were placed in a baby chair reclined at 50º from the horizontal The infants were shown four objects of different size and rigidity large rigid (RG), small rigid (RP), large soft (MG), and small soft (MP) for a period of 1 minute each. Reaching movements were recorded by three digital cameras and the images were analyzed by using the 3D movement reconstruction. A total of 378 reaches were analyzed in relation to the following variables: qualitative proximal and distal adjustments, hand preference, and grasping of objects ; and quantitative straightness index, mean velocity, movement units, and adjustment time index. Results: There were many different changes in reaching over age. The answers to stimulation and the grasping of objects increased. Proximal adjustments were shown to be variable. Hand preference changed from the left to the right. The hand was predominantly half-opened in both the beginning and the end of the reaches; however, hand opening angle increased in the end of the reaches from the fifth to the sixth month. In all the ages, hand orientation was predominantly oblique when touching the object, and vertical when grasping it. As regards the quantitative variables, the straightness index and the mean velocity increased, and the movement units decreased. No significant changes were observed in the adjustment time index. Infants performed bimanual movements for the large rigid object, and unimanual movements for the small ones. The adjustments were similar in relation to the large soft object. Right-hand preference was higher for the small objects. In the beginning of the reaches, the hand was predominantly half-opened for all the objects; while in the end of the reaches, the hand was predominantly opened for the object large rigid. Hand orientation was predominantly oblique when touching the object, and vertical when grasping it, especially for the object large rigid. The soft objects were more frequently grasped than the rigid ones. The straightness index was higher for the large soft object, while the adjustment time index and the number of movement units were lower for this same object. The number of movement units increased for the small objects. No significant changes were verified in the mean velocity. Conclusion: It is possible to suggest that reaching movements are improved over age, thus indicating an increase in the infants performance during the studied period of life. Once the infants perceive the object properties, they adjust the essential variables of their movements by using their available motor abilities, thus suggesting the existence of a complex perceptionaction coupling. / Vários estudos têm identificado que as propriedades dos objetos induzem ajustes no alcance; no entanto, poucos investigaram a influência específica do tamanho e rigidez dos objetos em lactentes jovens, principalmente empregando a análise cinemática. Objetivo: Verificar o efeito das propriedades de tamanho e rigidez dos objetos nas variáveis qualitativas e quantitativas do alcance de lactentes de 4 a 6 meses de idade, observando como essas variáveis mudam ao longo do tempo. Métodos: Nove lactentes saudáveis foram posicionados em uma cadeira infantil reclinada a 50o. Quatro objetos foram apresentados, um rígido grande (RG), um rígido pequeno (RP), um maleável grande (MG) e um maleável pequeno (MP), por um período de 1 minuto cada. Os movimentos de alcance foram filmados por três câmeras digitais e as imagens reconstruídas tridimensionalmente. Em um total de 378 alcances, foram analisadas as variáveis qualitativas ajustes proximais e distais, preferência manual e apreensão dos objetos e as variáveis quantitativas índice de retidão, velocidade média, unidades de movimento e índice de tempo de ajuste. Resultados: Constatou-se que, ao longo dos meses, houve aumento da resposta aos estímulos, apreensão dos objetos, variabilidade nos ajustes proximais e mudança na preferência manual da esquerda para a direita. A abertura da mão foi predominantemente a semi-aberta tanto no início quanto no final do alcance. Do quinto para o sexto mês, no entanto, observou-se aumento da mão aberta no final do movimento. A orientação oblíqua da mão no toque foi predominante em todos os meses e, na apreensão, a predominância foi a orientação vertical. Quanto às variáveis quantitativas, houve aumento no índice de retidão e na velocidade média, bem como diminuição das unidades de movimentos. Não foram observadas mudanças significativas no índice de ajustes do movimento. Constatouse ajuste bimanual para o objeto RG e unimanual para os objetos pequenos. Para o objeto MG, os ajustes foram semelhantes. A preferência manual à direita foi maior ao alcançar os objetos pequenos. No início do alcance, a mão semi-aberta foi predominante para todos os objetos e, no final do alcance, a mão aberta foi mais utilizada para o objeto RG. Constatou-se que a orientação da mão foi predominantemente oblíqua no toque dos objetos e, na apreensão, a predominância foi a vertical, principalmente para o objeto RG. Os objetos maleáveis foram mais apreendidos do que os rígidos. O índice de retidão foi maior para o objeto MG, enquanto o índice de tempo de ajuste e o número de unidades de movimentos foram menores. O número de unidades de movimento foi maior para os objetos pequenos. A velocidade média não foi modificada significativamente. Conclusão: Sugere-se que, ao longo dos meses, os movimentos de alcance são aprimorados, indicando ganho de performance no período de vida estudado. Os lactentes, ao perceberem as propriedades dos objetos, ajustam as variáveis essenciais do movimento a partir da capacidade motora que eles têm disponível nesse período de vida, sugerindo, assim, a existência de uma complexa interação percepção-ação.