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Mental rotation (MR) is the ability to transform a mental representation of an object so as to accurately predict how the object would look from a different angle (Sci 171:701-703, 1971), and it is involved in a number of important cognitive and behavioral activities. In this review we discuss recent studies that have examined MR in infants and the development of MR across the first year after birth. These studies have produced many conflicting results, yet several tentative conclusions can be reached. First, MR may be operational in infants as young as 3 months of age. Second, there may be sex differences in MR performance in infancy, in general favoring males, as there are in children and in adults. Third, there appear to be multiple influences on infants' MR performance, including infants' motor activity, stimulus or task complexity, hormones, and parental attitudes. We conclude by calling for additional research to examine more carefully the causes and consequences of MR abilities early in life.

Currently, a central problem for theoretical biology is the integration of development with genetics and evolutionary theory. Through the late 20th century, biologists held that animals resemble their ancestors strictly because of the transgenerational transmission of DNA. This view effectively wrote development out of evolutionary biology. However, many molecular and developmental biologists now understand that phenotypes – anatomical, physiological, and behavioral traits – are not determined by genes (i.e., DNA segments) alone; instead, they emerge epigenetically from developmental processes involving co-acting genetic factors, environmental factors, molecular epigenetic factors, and other non-genetic factors within organisms' bodies. This insight forces a rethinking of biological inheritance. Perspectives focusing on the dynamics of developmental systems offer a compelling alternative way to think about inheritance, providing a powerful substitute to the reductionistic framework that attributes phenotypic outcomes to genetic instructions set in advance of developmental processes. Rethinking genetics, epigenetics, and inheritance by focusing on the dynamics of developmental systems helps highlight the bidirectional effects of evolutionary and developmental processes on one another, yielding a more integrated understanding of development, inheritance, and evolution. Simultaneously, this approach encourages rejection of genetic determinism, a simplistic perspective that continues to appear in psychological writing, despite its biological implausibility. [ABSTRACT FROM AUTHOR]

Proponents of the Extended Evolutionary Synthesis (EES) emphasize the critical role that organisms and their development play in the process of evolution. This framework explicitly rejects the genocentric focus that once dominated interpretations of the Modern Synthesis in evolutionary theory. In place of genocentrism, EES highlights processes like niche construction, developmental constraint, and extragenetic inheritance as central to any understanding of the evolutionary process. However, much more is at stake in adopting the EES than simply moving beyond the gene-dominant viewpoint of the Modern Synthesis. The EES, in fact, represents a fundamental challenge to the core of classic Darwinism itself by actively repudiating Darwin's key idea that natural selection acts as a creative force in the construction of phenotypes and phenotypic change. In this paper, we more fully explore the assumptive base of Darwinism's population-oriented, selectional focus. We demonstrate how taking development seriously in evolutionary theory mandates a systematic overhaul of Darwinism's assumptive base in favor of grounding all understanding of phenotypic construction in the developmental processes of self-organization endemic to organisms' active engagement with their worlds. [ABSTRACT FROM AUTHOR]

Mental rotation (MR) is an important feature of spatial cognition invoking mental imagery of an object's appearance when viewed from a new orientation. Prior studies have revealed evidence of MR in infants, including a sex difference similar to that detected in older populations. Some of these studies used visual habituation methods whereby infants were familiarized with an object rotating through a 240° angle, followed by test trials showing either the habituation object or a mirror image object rotating through the previously unseen 120° angle. Significantly longer looking at either of these objects was taken to reflect infants' ability to recognize the habituation object even when seen from a novel viewpoint, suggesting the capacity for MR. However, these infants' responses could, in theory, be explained with reference to perceptual discrimination rather than MR, because the views of the habituation and test objects were very similar in some video frames. In the current study, we observed a diverse population of 5-month-olds (24 females, 24 males) for evidence of MR through 30° of arc. In this more challenging test, our stimuli left a 30° gap angle between critical video frames representing the habituation and test objects. Consistent with earlier reports, we found that relative to female infants, male infants looked significantly longer at the mirror image test stimulus immediately following habituation. These results add to an emerging consensus that some young infants are capable of MR, and that male and female infants on average behave differently in this type of MR task. [ABSTRACT FROM AUTHOR]

Some cognitive abilities exhibit reliable gender differences, with females outperforming males in specific aspects of verbal ability, and males showing an advantage on certain spatial tasks. Among these cognitive gender differences, differences in mental rotation are the most robust, and appear to be present even in infants. A large body of animal research suggests that gonadal hormones, particularly testosterone, during early development could contribute to this gender difference in mental rotation. Also, substantial evidence supports an influence of socialization on mental rotation performance. The present study investigated the relationship of two types of factors, early postnatal testosterone exposure and parental attitudes about gender, to mental rotation performance in 61 healthy infants (29 males, 32 females). We measured salivary testosterone at two time points: 1-2.5 months of age and 5-6 months of age. Infants' mental rotation performance and parents' attitudes about gender were assessed at 5-6 months of age. As predicted, testosterone concentrations were significantly higher in boys than girls in early infancy (d = 0.54), and boys performed significantly better than girls on mental rotation (d = 0.64). A significant positive correlation between testosterone at age 1-2.5 months and mental rotation was found only in boys (r = 0.50, p = 0.01). A significant negative correlation between parents' gender-stereotypical attitudes and mental rotation performance was found only in girls (r = -0.57, p = 0.002). These findings suggest that the early postnatal testosterone surge (also known as "mini-puberty") may have organizational influences on mental rotation performance in boys, and that parents may influence their daughters' mental rotation abilities beginning very early in life.

Although looking-time methods have long been used to measure infant attention and investigate aspects of cognitive development, steady-state visually evoked potential (SSVEP) measures may be more sensitive or practical in some contexts. Here, we demonstrate habituation of infants' SSVEP amplitudes to a flickering checkerboard stimulus, and recovery of attention upon presentation of a novel checkerboard stimulus. This modulation of SSVEP amplitude was more robust than the modulation of looking time. In addition, we provide evidence of enhanced SSVEPs in response to covertly attended checkerboards flickering in peripheral visual fields, even while infants are fixating a central stimulus. These experiments provide the first evidence of habituation and recovery of infant SSVEP amplitudes, as well as the first evidence of sustained infant covert attention using SSVEPs. SSVEPs may be a sensitive, efficient measure for use in studying early cognitive development, in particular infants' overt and covert attention.

Wynn's (1992) seminal research reported that infants looked longer at stimuli representing "incorrect" versus "correct" solutions of basic addition and subtraction problems and concluded that infants have innate arithmetical abilities. Since then, infancy researchers have attempted to replicate this effect, yielding mixed findings. The present meta-analysis aimed to systematically compile and synthesize all of the primary replications and extensions of Wynn (1992) that have been conducted to date. The synthesis included 12 studies consisting of 26 independent samples and 550 unique infants. The summary effect, computed using a random-effects model, was statistically significant, d = +0.34, p < 0.001, suggesting that the phenomenon Wynn originally reported is reliable. Five different tests of publication bias yielded mixed results, suggesting that while a moderate level of publication bias is probable, the summary effect would be positive even after accounting for this issue. Out of the 10 metamoderators tested, none were found to be significant, but most of the moderator subgroups were significantly different from a null effect. Although this meta-analysis provides support for Wynn's original findings, further research is warranted to understand the underlying mechanisms responsible for infants' visual preferences for "mathematically incorrect" test stimuli.

Over many years, we have published vibrational spectra of molecular materials at extreme pressure and temperature obtained using shock compression and coherent Raman spectroscopy methods. For diatomic molecules, we were able to extract vibrational temperatures from the intensities of spectrally resolved vibrational hot bands. Larger molecules in the condensed phase suffer band broadening effects that obscure the vibrational hot bands as the anharmonicities are typically smaller than the widths of the bands. This inability to resolve the hot bands inhibits the extraction of vibrational temperature and the measurement of the vibrational frequency of the fundamental. Here, we use a hot band model based on gas-phase anharmonic coupling coefficients to fit coherent anti-Stokes Raman spectra of the ν1 vibrational mode of shock compressed condensed phase N2O with shock pressures and temperatures estimated from literature equations of state and compare to fits from a model using a single Gaussian peak. We report the resulting vibrational frequency shifts with shock pressure. [ABSTRACT FROM AUTHOR]

Mental rotation involves transforming a mental image of an object so as to accurately predict how the object would look if it were rotated in space. This study examined mental rotation in male and female 3-month-olds, using the stimuli and paradigm developed by Moore and Johnson (2008). Infants were habituated to a video of a three-dimensional object rotating back and forth through a 240 degree angle around the vertical axis. After habituation, infants were tested both with videos of the same object rotating through the previously unseen 120 degree angle, and with the mirror image of that display. Unlike females, who fixated the test displays for approximately equal durations, males spent significantly more time fixating the familiar object than the mirror-image object. Because familiarity preferences like this emerge when infants are relatively slow to process a habituation stimulus, the data support the interpretation that mental rotation of dynamic three-dimensional stimuli is relatively difficult--but possible--for 3-month-old males. Interpretation of the sex differences observed in 3- and 5-month-olds' performances is discussed. (Contains 3 figures.)