Four-year-olds use a mixture of spatial reference frames

Keeping track of unseen objects is an important spatial skill. In order to do this, people must situate the object in terms of different frames of reference, including body position (egocentric frame of reference), landmarks in the surrounding environment (extrinsic frame reference), or other attached features (intrinsic frame of reference). Nardini et al. hid a toy in one of 12 cups in front of children, turned the array when they were not looking, and then asked them to point to the cup with the toy. This forced children to use the intrinsic frame (information about the array of cups) to locate the hidden toy. Three-year-olds made systematic errors by using the wrong frame of reference, 4-year-olds were at chance, and only 5- and 6-year-olds were successful. Can we better understand the developmental change that takes place at four years? This paper uses a modelling approach to re-examine the data and distinguish three possible strategies that could lead to the previous results at four years: (1) Children were choosing cups randomly, (2) Children were pointing between the egocentric/extrinsic-cued location and the correct target, and (3) Children were pointing near the egocentric/extrinsic-cued location on some trials and near the target on the rest. Results heavily favor the last possibility: 4-year-olds were not just guessing or trying to combine the available frames of reference. They were using the intrinsic frame on some trials, but not doing so consistently. These insights suggest that accounts of improving spatial performance at 4 years need to explain why there is a mixture of responses. Further application of the selected model also suggests that children become both more reliant on the correct frame and more accurate with any chosen frame as they mature

The Numeric Ebbinghaus Effect: Evidence for a Density-Area Mechanism of Numeric Estimation?

One model of numeric perception is a density-area mechanism: a process that estimates both density and area of an array, then multiplies them to create an estimate of number. One line of evidence that supports this is the surprising numeric Ebbinghaus illusion: smaller context circles lead to greater perceived number than larger context circles, potentially via larger perceived area. This registered report re-tested this effect with a number of simple but potentially important improvements in the method and analysis. Participants were asked to indicate the number of blue dots in arrays that were surrounded by grey context circles of three different sizes. Both experiments confirmed that larger context circles lead to a proportional increase in perceived number. Experiment 1 (N = 50) did so with denser, more texture-like arrays (50-100 dots filling 35% of the area). Experiment 2 (N = 50) did so with sparser, more scatter-like arrays (10-30 dots filling 5% of the area). These findings confirm the existence of the numeric Ebbinghaus effect. This in turn confirms a specific prediction derived from a density-area mechanism and rules out alternatives that begin by stripping away context to non-verbally count discrete entities. No further significant evidence was found to suggest that this depends on the array being particularly dense or texture-like, nor to suggest that anything moderates the impact of increasing perceived area as a direct proportional effect on increasing perceived number. This further builds the case that this kind of numeric perception relies on a density-area mechanism

Multisensory perception and decision-making with a new sensory skill

It is clear that people can learn a new sensory skill – a new way of mapping sensory inputs onto world states. It remains unclear how flexibly a new sensory skill can become embedded in multisensory perception and decision-making. To address this, we trained typically-sighted participants (N=12) to use a new echo-like auditory cue to distance in a virtual world, together with a noisy visual cue. Using model-based analyses, we tested for key markers of efficient multisensory perception and decision-making with the new skill. We found that twelve of fourteen participants learned to judge distance using the novel auditory cue. Their use of this new sensory skill showed three key features: (1) it enhanced the speed of timed decisions; (2) it largely resisted interference from a simultaneous digit span task; and (3) it integrated with vision in a Bayes-like manner to improve precision. We also show some limits following this relatively short training: precision benefits were lower than the Bayesoptimal prediction, and there was no forced fusion of signals. We conclude that people already embed new sensory skills in flexible multisensory perception and decision-making after a short training period. A key application of these insights is to the development of sensory augmentation systems that can enhance human perceptual abilities in novel ways. The limitations we reveal (sub-optimality, lack of fusion) provide a foundation for further investigations of the limits of these abilities and their brain basis

Coding Locations Relative to One or Many Landmarks in Childhood

Cognitive development studies how information processing in the brain changes over the course of development. A key part of this question is how information is represented and stored in memory. This study examined allocentric (world-based) spatial memory, an important cognitive tool for planning routes and interacting with the space around us. This is typically theorized to use multiple landmarks all at once whenever it operates. In contrast, here we show that allocentric spatial memory frequently operates over a limited spatial window, much less than the full proximal scene, for children between 3.5 and 8.5 years old. The use of multiple landmarks increases gradually with age. Participants were asked to point to a remembered target location after a change of view in immersive virtual reality. A k-fold cross-validation model-comparison selected a model where young children usually use the target location’s vector to the single nearest landmark and rarely take advantage of the vectors to other nearby landmarks. The comparison models, which attempt to explain the errors as generic forms of noise rather than encoding to a single spatial cue, did not capture the distribution of responses as well. Parameter fits of this new single- versus multi-cue model are also easily interpretable and related to other variables of interest in development (age, executive function). Based on this, we theorize that spatial memory in humans develops through three advancing levels (but not strict stages): most likely to encode locations egocentrically (relative to the self), then allocentrically (relative to the world) but using only one landmark, and finally, most likely to encode locations relative to multiple parts of the scene

Internal Biases Are Linked to Disrupted Cue Combination in Children and Adults

Cue combination describes the use of two sensory cues together to increase perceptual precision. Internal relative bias describes a situation in which two cues to the same state of the world are perceived as signalling different states of the world on average. Current theory and evidence have difficulty accounting for many instances where cue combination is absent, such as in children under 10 years old, and in a variety of tasks. Here we show that internal relative biases between cues could be a key explanatory factor. Experiment 1, studying children’s 3D (slant) perception via disparity and texture, found a negative cross-sectional correlation between internal relative bias and cue combination behaviour in 7-10 year olds. Strikingly, children who had below-median levels of internal relative bias were able to combine cues, unlike the typical result for that age range. Experiment 2, studying adults’ visual-auditory localisation, found that cue combination behaviour increased after an intervention designed to decrease internal relative bias. We interpret this as strong but preliminary evidence that internal relative bias can disrupt cue combination behaviour. This provides a plausible mechanism to explain why children under 10 generally do not combine cues, and why audio-visual cue combination is so inconsistent in adults. Moving forward, we suggest that researchers who fail to find an expected cue combination effect should further investigate the possibility of issues with internal relative bias. Decreasing internal relative bias may also be an important goal for rehabilitation and sensory substitution or augmentation approaches to promoting efficient multisensory perception

The real preschoolers of Orange County: Early number learning in a diverse group of children

The authors assessed a battery of number skills in a sample of over 500 preschoolers, including both monolingual and bilingual/multilingual learners from households at a range of socio-economic levels. Receptive vocabulary was measured in English for all children, and also in Spanish for those who spoke it. The first goal of the study was to describe entailment relations among numeracy skills by analyzing patterns of co-occurrence. Findings indicated that transitive and intransitive counting skills are jointly present when children show understanding of cardinality and that cardinality and knowledge of written number symbols are jointly present when children successfully use number lines. The study’s second goal was to describe relations between symbolic numeracy and language context (i.e., monolingual vs. bilingual contexts), separating these from well-documented socio-economic influences such as household income and parental education: Language context had only a modest effect on numeracy, with no differences detectable on most tasks. However, a difference did appear on the scaffolded number-line task, where bilingual learners performed slightly better than monolinguals. The third goal of the study was to find out whether symbolic number knowledge for one subset of children (Spanish/English bilingual learners from low-income households) differed when tested in their home language (Spanish) vs. their language of preschool instruction (English): Findings indicated that children performed as well or better in English than in Spanish for all measures, even when their receptive vocabulary scores in Spanish were higher than in English

Multisensory perception and decision-making with a new sensory skill

It is clear that people can learn a new sensory skill – a new way of mapping sensory inputs onto world states. It remains unclear how flexibly a new sensory skill can become embedded in multisensory perception and decision-making. To address this, we trained typically-sighted participants (N=12) to use a new echo-like auditory cue to distance in a virtual world, together with a noisy visual cue. Using model-based analyses, we tested for key markers of efficient multisensory perception and decision-making with the new skill. We found that twelve of fourteen participants learned to judge distance using the novel auditory cue. Their use of this new sensory skill showed three key features: (1) it enhanced the speed of timed decisions; (2) it largely resisted interference from a simultaneous digit span task; and (3) it integrated with vision in a Bayes-like manner to improve precision. We also show some limits following this relatively short training: precision benefits were lower than the Bayes-optimal prediction, and there was no forced fusion of signals. We conclude that people already embed new sensory skills in flexible multisensory perception and decision-making after a short training period. A key application of these insights is to the development of sensory augmentation systems that can enhance human perceptual abilities in novel ways. The limitations we reveal (sub-optimality, lack of fusion) provide a foundation for further investigations of the limits of these abilities and their brain basis