Emergence of the ability to discriminate a blue from gray at one month of age

Two different methods which minimize achromatic cues were used to test the ability of 1-month-olds to discriminate gray from broadband blue (lambda peak = 475-480 nm). Unlike the newborns we tested previously, 1-month-olds demonstrated the discrimination with both methods. In Experiment 1 they showed preferences for each of four blue-and-gray checkerboards over gray squares of the same mean luminance, even though the luminance of the gray checks was varied in small steps over a wide range. In Experiment 2 they looked longer at a blue square than at a gray square, after they had been habituated to five other gray squares of varying luminance. Compared to previous results, these data imply an improvement between birth and 1 month of age in the discrimination of gray from broadband blue. Possible physiological changes underlying this improvement are discussed.     

Analysis of timing variability in human movements by aligning parameter curves in time

The analysis of timing in human movements requires a reference with which timing can be quantified. In reactive movements this reference is given by the stimulus. However, many movements do not respond to such an external event. In throwing, for instance, the hand opening for release has to be timed to an acceleration of the throwing arm. A common approach to analyzing release-timing variability is to choose a landmark in the movement that is supposed to have a fixed temporal relation to the release. Such distinct landmarks, however, are not always well definable. Therefore, the present article describes an alternative approach analyzing timing variability on the basis of the alignment of different trials relative to their kinematic shape, by shifting the trials in the time domain. The basic assumption behind this approach is that single throwing movements are one instance of an acquired movement template, and thus show a considerable similarity. In contrast, the location of the temporal moment of release varies from trial to trial, generating imprecision regarding the release timing. In trials synchronized with respect to the release, this variability can be assessed by shifting the kinematic profiles of the throwing movements in time such that they superimpose as closely as possible. As a result, the corresponding time shifts for all trials represent a measure of the release time deviations across trials, and the standard deviation of these deviations represents the timing variability. Aside from timing analyses in such movements as throwing, the approach can be applied to very different tasks with timing demands—for example, to neurophysiological signals.     

The shape of boubas: sound-shape correspondences in toddlers and adults

A striking demonstration that sound–object correspondences are not completely arbitrary is that adults map nonsense words with rounded vowels (e.g. bouba) to rounded shapes and nonsense words with unrounded vowels (e.g. kiki) to angular shapes ( Köhler, 1947 ; Ramachandran & Hubbard, 2001 ). Here we tested the bouba/kiki phenomenon in 2.5‐year‐old children and a control group of adults (n =20 per age), using four pairs of rounded versus pointed shapes and four contrasting pairs of nonsense words differing in vowel sound. Overall, participants at both ages matched words with rounded vowels to the rounder shapes and words with unrounded vowels to the pointed shapes (both ps < .0005), with no significant difference between the two ages (p > .10). Such naturally biased correspondences between sound and shape may influence the development of language.     

Face Perception During Early Infancy

Previous studies of face perception during early infancy are difficult to interpret because of discrepant results and procedural differences. We used a standardized method based on the Teller acuity card procedure to test newborns, 6-week-olds, and 12-week-olds with three pairs of face and nonface stimuli modified from previous studies. Newborns' preferences were influenced both by the visibility of the stimuli and by their resemblance to a human face. There appears to be a mechanism, likely subcortical, predisposing newborns to look toward faces. Changes in preferences at 6 and 12 weeks of age suggest increasing cortical influence over infants' preferences for faces.     

Who is a thinker? With age,higher SES American children increasingly associate social status with divisions in labour

This exploratory report investigates how children, aged 6- to 12-years, reason about divisions in labour. It focuses on understanding when in development children might associate higher status groups with intellectual as opposed to physical labour. It explores this question by introducing a sample of mostly mid/high-SES American children to a novel factory setting and then asking them who is likely to have one of two jobs: a ‘builder’ (physical labour), or ‘thinker’ (intellectual labour) job. Older children were more likely than younger children to associate an individual's higher social status with intellectual labour work as opposed to physical labour work. Children also explained their reasoning, and with age their explanations focused more on social factors like the role of access to ‘choices’ or opportunities in shaping the nature of others' work.     

Socioeconomic status and executive function in early childhood: Exploring proximal mechanisms

Although there is substantial evidence that socioeconomic status (SES) predicts children's executive function (EF), the mechanisms underlying this association are poorly understood. This study tested the utility of two theories proposed to link SES to children's EF: the family stress model and the family investment model. Data came from the Midwestern Infant Development Study (N = 151). To measure SES, parental education and income were assessed during pregnancy, and income was also assessed when children were 6 and 36 months old. Children's EF, operationalized as working memory/inhibitory control (WMIC) and self‐control, was assessed at 36 months of age, along with potential mediators including maternal psychological distress, harsh parenting, and cognitive stimulation. Using structural equation modeling, we tested simultaneous pathways from SES to EF: (a) via maternal psychological distress to harsh parenting (family stress model) and (b) via cognitive stimulation (family investment model). Of the SES measures, lower education predicted poorer WMIC directly and indirectly via greater maternal psychological distress. Lower education also predicted poorer self‐control via greater maternal psychological distress. This effect was partially suppressed by an indirect path from lower education to better self‐control via greater psychological distress and increased harsh parenting. Cognitive stimulation did not act as a mediator. Income was not directly or indirectly associated with EF. These findings provide partial support for the family stress model and suggest that family functioning is an important proximal mechanism for children's EF development. This study also highlights the importance of considering SES as a multidimensional construct.     

Multisensory spatial representations in eye-centered coordinates for reaching

Humans can reach for objects with their hands whether the objects are seen, heard or touched. Thus, the position of objects is recoded in a joint-centered frame of reference regardless of the sensory modality involved. Our study indicates that this frame of reference is not the only one shared across sensory modalities. The location of reaching targets is also encoded in eye-centered coordinates, whether the targets are visual, auditory, proprioceptive or imaginary. Furthermore, the remembered eye-centered location is updated after each eye and head movement. This is quite surprising since, in principle, a reaching motor command can be computed from any non-visual modality without ever recovering the eye-centered location of the stimulus. This finding may reflect the predominant role of vision in human spatial perception.