Infants' use of category knowledge and object attributes when segregating objects at 8.5 months of age

The current research investigates infants' perception of a novel object from a category that is familiar to young infants: key rings. We ask whether experiences obtained outside the lab would allow young infants to parse the visible portions of a partly occluded key ring display into one single unit, presumably as a result of having categorized it as a key ring. This categorization was marked by infants' perception of the keys and ring as a single unit that should move together, despite their attribute differences. We showed infants a novel key ring display in which the keys and ring moved together as one rigid unit (Move-together event) or the ring moved but the keys remained stationary throughout the event (Move-apart event). Our results showed that 8.5-month-old infants perceived the keys and ring as connected despite their attribute differences, and that their perception of object unity was eliminated as the distinctive attributes of the key ring were removed. When all of the distinctive attributes of the key ring were removed, the 8.5-month-old infants perceived the display as two separate units, which is how younger infants (7-month-old) perceived the key ring display with all its distinctive attributes unaltered. These results suggest that on the basis of extensive experience with an object category, infants come to identify novel members of that category and expect them to possess the attributes typical of that category.     

Precocious quantitative cognition in monkeys

Basic quantitative abilities are thought to have an innate basis in humans partly because the ability to discriminate quantities emerges early in child development. If humans and nonhuman primates share this developmentally primitive foundation of quantitative reasoning, then this ability should be present early in development across species and should emerge earlier in monkeys than in humans because monkeys mature faster than humans. We report that monkeys spontaneously make accurate quantity choices by 1 year of age in a task that human children begin to perform only at 2.5 to 3 years of age. Additionally, we report that the quantitative sensitivity of infant monkeys is equal to that of the adult animals in their group and that rates of learning do not differ between infant and adult animals. This novel evidence of precocious quantitative reasoning in infant monkeys suggests that human quantitative reasoning shares its early developing foundation with other primates. The data further suggest that early developing components of primate quantitative reasoning are constrained by maturational factors related to genetic development as opposed to learning experience alone.     

Adding up the effects of cultural experience on the brain

How does the brain represent number and perform mathematical calculations? According to a recent and provocative study by Tang and colleagues, it depends on which language you learn. They found that the divergent linguistic and cultural experiences of native Chinese and native English speakers are associated with distinct patterns of brain activity during mathematical processing. Their results raise important questions about the cognitive and neural specificity of cultural influences on mathematical processes and the core nature of mathematical cognition.     

Spontaneous analog number representations in 3‐year‐old children

When enumerating small sets of elements nonverbally, human infants often show a set‐size limitation whereby they are unable to represent sets larger than three elements. This finding has been interpreted as evidence that infants spontaneously represent small numbers with an object‐file system instead of an analog magnitude system ( Feigenson, Dehaene & Spelke, 2004 ). In contrast, non‐human animals and adult humans have been shown to rely on analog magnitudes for representing both small and large numbers ( Brannon & Terrace, 1998 ; Cantlon & Brannon, 2007 ; Cordes, Gelman, Gallistel & Whalen, 2001). Here we demonstrate that, like adults and non‐human animals, children as young as 3 years of age spontaneously employ analog magnitude representations to enumerate both small and large sets. Moreover, we show that children spontaneously attend to numerical value in lieu of cumulative surface area. These findings provide evidence of young children’s greater sensitivity to number relative to other quantities and demonstrate continuity in the process they spontaneously recruit to judge small and large values.     

Continuity and change in children's longitudinal neural responses to numbers

Human children possess the ability to approximate numerical quantity nonverbally from a young age. Over the course of early childhood, children develop increasingly precise representations of numerical values, including a symbolic number system that allows them to conceive of numerical information as Arabic numerals or number words. Functional brain imaging studies of adults report that activity in bilateral regions of the intraparietal sulcus (IPS) represents a key neural correlate of numerical cognition. Developmental neuroimaging studies indicate that the right IPS develops its number‐related neural response profile more rapidly than the left IPS during early childhood. One prediction that can be derived from previous findings is that there is longitudinal continuity in the number‐related neural responses of the right IPS over development while the development of the left IPS depends on the acquisition of numerical skills. We tested this hypothesis using fMRI in a longitudinal design with children ages 4 to 9. We found that neural responses in the right IPS are correlated over a 1–2‐year period in young children whereas left IPS responses change systematically as a function of children's numerical discrimination acuity. The data are consistent with the hypothesis that functional properties of the right IPS in numerical processing are stable over early childhood whereas the functions of the left IPS are dynamically modulated by the development of numerical skills.     

How much does number matter to a monkey (Macaca mulatta)?

Although many animal species can represent numerical values, little is known about how salient number is relative to other object properties for nonhuman animals. In one hypothesis, researchers propose that animals represent number only as a last resort, when no other properties differentiate stimuli. An alternative hypothesis is that animals automatically, spontaneously, and routinely represent the numerical attributes of their environments. The authors compared the influence of number versus that of shape, color, and surface area on rhesus monkeys' (Macaca mulatta) decisions by testing them on a matching task with more than one correct answer: a numerical match and a nonnumerical (color, surface area, or shape) match. The authors also tested whether previous laboratory experience with numerical discrimination influenced a monkey's propensity to represent number. Contrary to the last-resort hypothesis, all monkeys based their decisions on numerical value when the numerical ratio was favorable.     

Cognitive imitation in 2-year-old children (<Emphasis Type="Italic">Homo sapiens</Emphasis>): a comparison with rhesus monkeys (<Emphasis Type="Italic">Macaca mulatta</Emphasis>)

Here we compare the performance of 2-year-old human children with that of adult rhesus macaques on a cognitive imitation task. The task was to respond, in a particular order, to arbitrary sets of photographs that were presented simultaneously on a touch sensitive video monitor. Because the spatial position of list items was varied from trial to trial, subjects could not learn this task as a series of specific motor responses. On some lists, subjects with no knowledge of the ordinal position of the items were given the opportunity to learn the order of those items by observing an expert model. Children, like monkeys, learned new lists more rapidly in a social condition where they had the opportunity to observe an experienced model perform the list in question, than under a baseline condition in which they had to learn new lists entirely by trial and error. No differences were observed between the accuracy of each species' responses to individual items or in the frequencies with which they made different types of errors. These results provide clear evidence that monkeys and humans share the ability to imitate novel cognitive rules (cognitive imitation).     

Shared system for ordering small and large numbers in monkeys and humans

There is increasing evidence that animals share with adult humans and perhaps human infants a system for representing objective number as psychological magnitudes that are an analogue of the quantities they represent. Here we show that rhesus monkeys can extend a numerical rule learned with the values 1 through 9 to the values 10, 15, 20, and 30, which suggests that there is no upper limit on a monkey's numerical capacity. Instead, throughout the numerical range tested, both accuracy and latency in ordering two numerical values were systematically controlled by the ratio of the values compared. In a second experiment, we directly compared humans' and monkeys' performance in the same ordinal comparison task. The qualitative and quantitative similarity in their performance provides the strongest evidence to date of a single nonverbal, evolutionarily primitive mechanism for representing and comparing numerical values.     

Evolutionary Constraints on Human Object Perception

Language and culture endow humans with access to conceptual information that far exceeds any which could be accessed by a non‐human animal. Yet, it is possible that, even without language or specific experiences, non‐human animals represent and infer some aspects of similarity relations between objects in the same way as humans. Here, we show that monkeys’ discrimination sensitivity when identifying images of animals is predicted by established measures of semantic similarity derived from human conceptual judgments. We used metrics from computer vision and computational neuroscience to show that monkeys’ and humans’ performance cannot be explained by low‐level visual similarity alone. The results demonstrate that at least some of the underlying structure of object representations in humans is shared with non‐human primates, at an abstract level that extends beyond low‐level visual similarity. Because the monkeys had no experience with the objects we tested, the results suggest that monkeys and humans share a primitive representation of object similarity that is independent of formal knowledge and cultural experience, and likely derived from common evolutionary constraints on object representation.