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The Role of Motor Skills in the Development of Mental Rotation Abilities from Infancy to Preschool Age
(2026-05) Asokan, Tharanirakshita
From the earliest months of life, infants are captivated by objects, exploring them from multiple perspectives, grasping toys, chasing rolling balls, and anticipating their paths (Örnkloo & von Hofsten, 2007). These behaviours illustrate the emergence of visuospatial understanding and the formation of mental representations of objects and their movement. A foundational visuospatial process underlying these abilities is mental rotation (MR), defined as the capacity to mentally transform and manipulate objects in space (Linn & Petersen, 1985). Given MR’s pervasive role in everyday activities and its predictive power for mathematical thinking and later academic success (Wai et al., 2009), understanding its developmental course is both scientifically significant and practically valuable. Despite MR’s importance, the development trajectory of three-dimensional mental rotation (3D-MR) remains poorly understood. While cross-sectional studies demonstrate the emergence of 3D-MR in infants (Johnson & Moore, 2020) and its further development in preschoolers (Frick et al., 2013a), longitudinal investigations tracing its continuity across these two early stages are scarce. This gap is particularly surprising as the preschool years are a critical period for preparing children for formal schooling. Although infant studies highlight close links between motor development and 3D-MR (Schwarzer et al., 2013b), it remains unclear whether these early motor experiences (such as self-produced locomotion) have lasting predictive relations with 3D-MR into the preschool years. Additionally, it remains unclear whether concurrent links between motor skills and 3D-MR are also present in preschool children. Moreover, visuospatial processing encompasses intra-object processing (such as MR) and inter-object processing (such as prediction of object trajectories), both relying on the construction and transformation of spatial representations (Newcombe et al., 2013). Yet these two processes have been studied in isolation, leaving their developmental interrelations unexamined. This dissertation provides a comprehensive investigation of 3D-MR development from infancy (9 months) to preschool ages (4-6 years), integrating longitudinal and cross-sectional approaches across three empirical studies employing age- appropriate yet conceptually comparable 3D-MR tasks. Study 1 examined the longitudinal developmental trajectory of 3D-MR from infancy to preschool age (using screen-based tasks) and investigated the role of early motor experience. Results revealed infants who demonstrated stronger 3D-MR performance at 9 months of age, particularly those who had acquired crawling ability, also showed better 3D-MR performance at 4 to 6 years of age, providing potentially the first evidence for a longitudinal link between 3D-MR abilities across these developmental stages and highlighting the long-term relevance of early self-produced locomotion. Study 2 explored the relationship between motor skills and 3D-MR (employing a novel block-based 3D-MR task) during the preschool years using a cross-sectional design. The study revealed a developmentally nuanced pattern: associations between 3D-MR and gross motor skills were observed in younger preschoolers (4.6–5.5 years), whereas associations with fine motor skills emerged only in older preschoolers (5.6–6.5 years). These findings suggest a developmental shift in the motor foundations supporting spatial transformation abilities during early childhood. Study 3, explored the relationship between intra-object and inter-object processing during infancy. Although nodirect association between prediction ability and 3D-MR was observed, likely reflecting differences in task demands and representational requirements, self-produced locomotion was associated with infants’ visual prediction abilities. This finding converges with Study 1 and highlights the potential role of locomotor experience in early visuospatial development, while opening avenues for future research. Beyond its empirical contributions, this dissertation makes a significant methodological advance by developing age-appropriate and conceptually comparable 3D-MR tasks that can be used across infancy and preschool age. Notably, these tasks are one of the first 3D-MR paradigms, to demonstrate reliable angular disparity effects in preschool-aged children using both screen-based and tangible stimuli. Taken together, these findings provide a developmentally grounded account of 3D-MR in early years of life. By demonstrating longitudinal continuity in 3D-MR, enduring links with self-produced locomotion, motor proficiency, and interplay of perception and action, the present work offers compelling support for embodied theories of spatial cognition. Beyond advancing theoretical understanding, these findings have important implications for educational practice and early intervention. Given the well-established links between MR, STEM achievement, and broader academic success (Uttal et al., 2013), clarifying the perceptual-motor foundations of spatial thinking may inform developmentally sensitive strategies and targeted interventions to support spatial skill development, particularly for children at risk of delay, thereby promoting more equitable educational outcomes.
Irrigation-nutrition linkages under public and farmer-led irrigation arrangements in rural Kenya
(2026) Kiratu, Nixon Murathi
While great progress had been achieved under the Millennium Development Goals, owing to global crises such as the Covid-19 pandemic, climate change and ongoing wars, the global food and nutrition crisis is deteriorating and the number of undernourished people is bound to increase by the year 2030 which is a significant year in eradicating hunger and malnutrition under the Sustainable Development Goals. Conversely, despite its land and water resources, sub-Saharan Africa remains the region with the highest prevalence of undernourishment in the world in absolute terms. In this regard, irrigation has increasingly gained interest as a pivotal solution for the region due to its ability to increase agricultural output, galvanize production from weather and climatic risks and bring underutilized water-stressed lands into cultivation. However, the debate about what kind of irrigation to implement in sub-Saharan Africa and its purposed effect has been a matter of discussion in the global and African policy arena given that irrigation has been in the past considered as a single input factor that disregards irrigation arrangements (i.e. socio-technical set-up in which irrigation takes place (referred herein as irrigation arrangements). Furthermore, the linkage between irrigation and nutrition is still vaguely understood and remain largely understudied. In this regard, postulating that production diversity, farm income and women empowerment as the three vital nutrition pathways, this study investigated the linkages between irrigation and nutrition in a manner that takes into account various socio-technical irrigation arrangements and their differential effects on dietary diversity. Using complementary data collection techniques comprising of reconnaissance visits, key informant interviews, focus group discussions and a household survey, cross-sectional data was collected from smallholder farm households in farmer-led irrigation (FLI), public irrigation scheme (PIS) arrangements and non-irrigators in rural Kenya. To analyze the data, the study utilized descriptive statistics and econometric approaches comprising of probit model, multinomial logit regression (MNL), propensity score matching approach (PSM) and a three-stage least squares regression (3SLS). The results from the descriptive statics, probit model and MNL showed that the household socioeconomic factors that affect irrigation and irrigation arrangements were not only different but also different in the direction of effect for the same regressors. The PSM analyses showed that the FLI and PIS arrangements have a positive effect on farm income and dietary diversity. Further analyses using the 3SLS showed that the FLI leads to a more diverse household diet through the farm income and women’s empowerment pathways while the PIS households achieved it only through the women’s empowerment pathway. On the contrary, PIS was found to reduce production diversity and lead to a decrease in dietary diversity through this pathway. This study provided a strong basis to conclude that irrigation positively affects the irrigating households’ farm income and nutrition outcomes at household level across both irrigation arrangements in the context of smallholder agriculture in the study area. In contrast, irrigation was found to negatively affect the production diversity for the farm households in the PIS as well as their dietary diversity while it was not significant for the FLI and neither influenced their dietary diversity. Conspicuously, the feasibility of the women’s empowerment as an irrigation-nutrition pathway in both irrigation arrangements shows the importance of this pathway in improving the nutrition of irrigating households. Therefore, policy should take cognizance of the irrigation arrangements when promoting irrigation as a viable intervention towards production diversity, farm income and women empowerment as well as a means of improving smallholder farm households’ nutrition outcomes. Additionally, there is need to complementary intervene enabling factors that aide irrigating households achieve nutrition outcomes, such as through the markets for the farm income pathways and factors such as decision making, ownership of assets, credit access and decisions, control over use of income, leadership and workload for the women’s empowerment pathways. As regards research and policy analysis, the differences in production, income, women’s empowerment and nutrition outcomes between farmers in different irrigation arrangements needs to be investigated rather than a unitary approach to irrigation as well as a revision of the policy instruments in Kenya to recognize and support farmer-led irrigation arrangement.
Gaze when walking to grasp an object in the presence of obstacles
(2025) Voudouris, Dimitris; Brenner, Eli
People generally look at positions that are important for their current actions, such as objects they intend to grasp. What if there are obstacles on their path to such objects? We asked participants to walk into a room and pour the contents of a cup placed on a table into another cup elsewhere on the table. There were two small obstacles on the floor between the door and the table. There was a third obstacle on the table near the target cup. Participants often looked at the items on the table from the beginning, but, as they approached and entered the room, they often looked at the floor near the obstacles, although there was nothing particularly informative to see there. Thus they primarily relied on peripheral vision and memory of where they had seen obstacles to avoid knocking over the obstacles. As they approached the table, they mainly looked at the object that they intended to grasp and the obstacle near it. We conclude that people mainly look at positions at which they plan to physically interact with the environment, rather than at items that constrain such interactions.
Association of 37 markers of ultra-processing with all-cause mortality : a prospective cohort study in the UK Biobank
(2025) Krost, Kathrin Marie; Eichner, Gerrit; Fasshauer, Mathias; Eise, Nathalie Judith
Background: In contrast to ultra-processed foods (UPFs), the association between specific markers of ultra-processing (MUPs) and all-cause mortality remains unexplored. As MUPs such as flavour, emulsifier, and sweetener may contribute differently to health outcomes, evaluating their individual associations with mortality is crucial. Methods: This population-based, prospective, exploratory cohort study included 186,744 UK Biobank participants aged 40 to 75, recruited between 2006 and 2010, each of whom completed at least one Oxford WebQ. To assess intake of UPFs and specific MUPs, up to ten matching commercial products were researched for each Oxford WebQ item and analysed concerning 57 previously described MUPs grouped into nine MUP categories. Of these, 37 specific MUPs were identified in one or more products. A food item was regarded as UPF if it contained at least one MUP. Cox proportional hazard regression models for all-cause mortality were applied, incorporating gram intake from UPFs, as well as from foods containing each of the nine MUP categories and 37 specific MUPs, in relation to gram total food intake (expressed as percentage of total food intake (%TFI)), using penalised cubic splines. The hazard ratio (HR)-nadir was defined as the lowest HR on the %TFI axis and rescaled to 1. Findings: Over a mean follow-up of 11.0 years, 10,203 deaths occurred. Five MUP categories were significantly (linear P < 0.05) related to all-cause mortality and the following HRs (confidence interval (CI)) were observed relative to the HR-nadir: flavour (40% versus 10 %TFI (HR-nadir); HR (CI) 1.20 (1.08 to 1.33); P < 0.0011), flavour enhancer (2% versus 0 %TFI; 1.07 (1.00 to 1.16); P = 0.025), colouring agent (20% versus 3 %TFI; 1.24 (1.10 to 1.39); P < 0.0001), sweetener (20% versus 0 %TFI; 1.14 (1.06 to 1.23); P < 0.0043), and varieties of sugar (10% versus 4 %TFI; 1.10 (1.03 to 1.16); P = 0.025). Furthermore, 13 specific MUPs were significantly associated with all-cause mortality (linear and/or non-linear P < 0.05), i.e., glutamate, ribonucleotide, acesulfame, saccharin, sucralose, caking agent, firming agent, gelling agent, thickener, fructose, inverted sugar, lactose, and maltodextrin. Among these, gelling agent was inversely associated with mortality risk. UPF intake was significantly (P < 0.05) associated with all-cause mortality. Major findings remained robust in sensitivity analyses. Interpretation: Total MUP-based definition UPF, five MUP categories, and several specific MUPs within these categories were significantly associated with all-cause mortality. Thus, interventions targeting UPF may be most effective when focused on these candidates, which should also be prioritised for future mechanistic studies.
Low-level features predict perceived similarity for naturalistic images
(2025) A-Izzeddin, Emily J; Wallis, Thomas SA; Mattingley, Jason B; Harrison, William J
The mechanisms by which humans perceptually organize individual regions of a visual scene to generate a coherent scene representation remain largely unknown. Our perception of statistical regularities has been relatively well-studied in simple stimuli, and explicit computational mechanisms that use low-level image features (e.g., luminance, contrast energy) to explain these perceptions have been described. Here, we investigate to what extent observers can effectively use such low-level information present in isolated naturalistic scene regions to facilitate associations between said regions. Across two experiments, participants were shown an isolated reference patch, then required to select which of two subsequently presented patches came from the same scene as the reference (two-alternative forced choice method). In Experiment 1, participants made their judgments based on unaltered image patches, and were consistently above chance when performing such association judgments. Additionally, participants’ responses were well-predicted by a generalized linear multilevel model using predictors based on low-level feature similarity metrics (specifically, pixel-wise luminance and phase-invariant structure correlations). In Experiment 2, participants were presented with unaltered image regions, thresholded image regions, or regions reduced to only their edge content. Performance for thresholded and edge regions was significantly poorer than for unaltered image regions. Nonetheless, the model still correlated well with participants’ judgments. Our findings suggest that image region associations can be accounted for using low-level feature correlations, suggesting such basic features are strongly associated with those underlying judgments made for complex visual stimuli.