Individuating quantities

Philosophical Studies - When discrepancies are discovered between the outcomes of different measurement procedures, two sorts of explanation are open to scientists. Either (i) some of the outcomes...     

Monkeys match and tally quantities across senses

We report here that monkeys can actively match the number of sounds they hear to the number of shapes they see and present the first evidence that monkeys sum over sounds and sights. In Experiment 1, two monkeys were trained to choose a simultaneous array of 1-9 squares that numerically matched a sample sequence of shapes or sounds. Monkeys numerically matched across (audio-visual) and within (visual-visual) modalities with equal accuracy and transferred to novel numerical values. In Experiment 2, monkeys presented with sample sequences of randomly ordered shapes or tones were able to choose an array of 2-9 squares that was the numerical sum of the shapes and sounds in the sample sequence. In both experiments, accuracy and reaction time depended on the ratio between the correct numerical match and incorrect choice. These findings suggest monkeys and humans share an abstract numerical code that can be divorced from the modality in which stimuli are first experienced.     

Estimating and operating on discrete quantities in orangutans (Pongo pygmaeus)

This study investigated the ability of 3 male orangutans (Pongo pygmaeus; 1 subadult, 2 adults) to estimate, compare, and operate on 2 sets of small quantities (1-6 cereal bits). Experiment 1 investigated the orangutans' ability to choose the larger of 2 quantities when they were presented successively as opposed to simultaneously, thus being perceptually unavailable at the time of choice. Experiment 2 investigated the orangutans' ability to select the larger quantity after the original quantities were augmented or reduced. Orangutans were capable of selecting the larger of 2 quantities in Experiment 1. There was also some evidence from Experiment 2, albeit weaker, that orangutans may mentally combine quantities (but not dissociate) to obtain the larger of 2 quantities. This study suggests that orangutans use a representational mechanism (especially when comparing quantities) to select the larger of 2 sets of items.     

Priming reveals differential coding of symbolic and non-symbolic quantities

Number processing is characterized by the distance and the size effect, but symbolic numbers exhibit smaller effects than non-symbolic numerosities. The difference between symbolic and non-symbolic processing can either be explained by a different kind of underlying representation or by parametric differences within the same type of underlying representation. We performed a primed naming study to investigate this issue. Prime and target format were manipulated (digits or collections of dots) as well as the numerical distance between prime and target value. Qualitatively different priming patterns were observed for the two formats, showing that the underlying representations differed in kind: Digits activated mental number representations of the place coding type, while collections of dots activated number representations of the summation coding type.     

Children’s multiplicative transformations of discrete and continuous quantities

Recent studies have documented an evolutionarily primitive, early emerging cognitive system for the mental representation of numerical quantity (the analog magnitude system). Studies with nonhuman primates, human infants, and preschoolers have shown this system to support computations of numerical ordering, addition, and subtraction involving whole number concepts prior to arithmetic training. Here we report evidence that this system supports children’s predictions about the outcomes of halving and perhaps also doubling transformations. A total of 138 kindergartners and first graders were asked to reason about the quantity resulting from the doubling or halving of an initial numerosity (of a set of dots) or an initial length (of a bar). Controls for dot size, total dot area, and dot density ensured that children were responding to the number of dots in the arrays. Prior to formal instruction in symbolic multiplication, division, or rational number, halving (and perhaps doubling) computations appear to be deployed over discrete and possibly continuous quantities. The ability to apply simple multiplicative transformations to analog magnitude representations of quantity may form a part of the toolkit that children use to construct later concepts of rational number.     

Emergence: selection,allowed operations,and conserved quantities

We treat emergence via reference to four ideas: (1) the different levels of emergence are characterised by distinct conservation laws, (2) the emergence process starts from some instability, (3) the driving force of emergence is given by selection processes allowing canalisation of specific (emerging) paths, and (4) new forms of stability are determined by new kinds of operations. At a quantum-mechanical level entropy is conserved in an isolated system or at global level and the only allowed operations are local shifts in order and disorder – that implies weakening and strengthening correlations. The stable state is here represented by a highly symmetric state. Emergence of the classical physical world arises when energy is conserved and allowable operations include building and breaking of physical-chemical connections. The stable state is here the energy minimum. Emergence of the biotic world implies that the conserved quantity is energy efficiency. Energy is no longer locally conserved. The allowed operations are those that are consistent with the survival (persistence) of the organism. The emergence of the mind is grounded in selecting those operations that are rational (in the sense of maintaining biological self-organisation). Here, the rational value of behaviour is the quantity of interest. Mounting the ladder of (both cosmic and biological) evolution means to have more and more selection of the possible outcomes (and therefore of the relative operations) but in a growing space of possibilities: if selection would reduce more and more the space of possibilities, the final result would be a rigid order; at the other extreme, if we had only expansion of the possibilities without selection, the final result would be disorder. So growing complexity can be understood as a path in the evolutionary landscape of the systems in which a balance of order and disorder is maintained although each level emerges as a result of the selection.     

Technical note on the joint receipt of quantities of a single good

The joint receipt of x and y is the fact of receiving them both. If x and y are objects that are valued, their joint receipt is valued as well. Assumming joint receipt is a binary operation that satisfies the conditions of extensive measurement, there is a numerical representation that is additive over joint receipt. We consider the case where x and y are quantities of the same infinitely divisible good. Different sets of assumptions are explored. Invariance with respect to multiplication proves to be interesting. Invariance with respect to addition yields a linear form. A relaxation of the latter yields an approximately linear form. Finally, we consider a non-commutative but bisymmetric joint-receipt operation with a representation arising from preferences over gambles.     

Tactile enumeration of small quantities using one hand

Our study explores various aspects of enumerating small quantities in the tactile modality. Fingertips of one hand were stimulated by a vibro-tactile apparatus (for 100/800 ms). Between 1 and 5 stimuli were presented to the right or the left hand and applied to neighboring (e.g., thumb–index–middle) or non-neighboring (e.g., thumb–middle–pinkie) fingers. The results showed a moderate increase in RT up to 4 stimuli and then a decrease for 5 stimuli. Right hand stimulation evoked more accurate performance than left hand stimulation only under short exposures (100 ms). Importantly, when the stimuli were presented to neighboring fingers, the accuracy rate was higher and the RT was faster than when presented to non-neighboring fingers. We discuss the results and suggest that when the stimuli are presented to one hand the subitizing range is 4 rather than 3. Furthermore, the right hand advantage and the efficiency for neighboring fingers are further support for the association between number and spatial arrangement of the fingers.     

Intensive quantities: Why they matter to developmental research

A distinction can be drawn between extensive and intensive quantities. Extensive quantities (e.g., volume, distance), which have been the focus of developmental research, depend upon additive combination. Intensive quantities (e.g., density, speed), which have been relatively neglected, derive from proportional relations between variables. Thus, while proportional relations can be expressed with extensive quantities, these relations are constitutive with intensive quantities. One consequence is that factors, which are theorized as marginal with extensive quantities, are conceptually central in intensive contexts, and may need to be recognized in developmental models. Two such factors, termed variable salience and relational focus, are examined here, via a study where 963 Scottish children aged 7–12 years were asked to solve 42 intensive quantity problems in comparison and missing value format. Reasoning improved with age, but at all ages it was strongly influenced by variable salience and relational focus. Moreover, the manner in which these two factors interacted with other factors differed from what might be expected from models of proportional reasoning with extensive quantities. Based upon these results, it is argued that the distinction between extensive and intensive quantities is theoretically significant, and intensive quantities need to be granted more attention in the future.     

Hoping for more: The influence of outcome desirability on information seeking and predictions about relative quantities

People must often engage in sequential sampling in order to make predictions about the relative quantities of two options. We investigated how directional motives influence sampling selections and resulting predictions in such cases. We used a paradigm in which participants had limited time to sample items and make predictions about which side of the screen contained more of a critical item. Sampling selections were biased by monetary desirability manipulations, and participants exhibited a desirability bias for both dichotomous and continuous predictions.     

Chimpanzees (Pan troglodytes) accurately compare poured liquid quantities

Although many studies have shown that nonhuman animals can choose the larger of two discrete quantities of items, less emphasis has been given to discrimination of continuous quantity. These studies are necessary to discern the similarities and differences in discrimination performance as a function of the type of quantities that are compared. Chimpanzees made judgments between continuous quantities (liquids) in a series of three experiments. In the first experiment, chimpanzees first chose between two clear containers holding differing amounts of juice. Next, they watched as two liquid quantities were dispensed from opaque syringes held above opaque containers. In the second experiment, one liquid amount was presented by pouring it into an opaque container from an opaque syringe, whereas the other quantity was visible the entire time in a clear container. In the third experiment, the heights at which the opaque syringes were held above opaque containers differed for each set, so that sometimes sets with smaller amounts of juice were dropped from a greater height, providing a possible visual illusion as to the total amount. Chimpanzees succeeded in all tasks and showed many similarities in their continuous quantity estimation to how they performed previously in similar tasks with discrete quantities (for example, performance was constrained by the ratio between sets). Chimpanzees could compare visible sets to nonvisible sets, and they were not distracted by perceptual illusions created through various presentation styles that were not relevant to the actual amount of juice dispensed. This performance demonstrated a similarity in the quantitative discrimination skills of chimpanzees for continuous quantities that matches that previously shown for discrete quantities.     

How young children pour equal quantities: A case of pseudocompensation

Two experiments are reported on how 3- to 4.5-year-old children pour equal liquid quantities. An apparent precocity and a decline with age in the ability to judge correctly when different-sized glasses contain the same amount of liquid is demonstrated in Experiment 1. Children of different ages use different strategies to make judgments of equality and this is revealed in Experiment 2. The most primitive strategy fortuitously led the youngest children to make a correct response in Experiment 1 but led to incorrect responses in Experiment 2. Possible explanations of these results are discussed.     

Configured-groups hypothesis: fast comparison of exact large quantities without counting

Our innate number sense cannot distinguish between two large exact numbers of objects (e.g., 45 dots vs 46). Configured groups (e.g., 10 blocks, 20 frames) are traditionally used in schools to represent large numbers. Previous studies suggest that these external representations make it easier to use symbolic strategies such as counting ten by ten, enabling humans to differentiate exactly two large numbers. The main hypothesis of this work is that configured groups also allow for a differentiation of large exact numbers, even when symbolic strategies become ineffective. In experiment 1, the children from grade 3 were asked to compare two large collections of objects for 5 s. When the objects were organized in configured groups, the success rate was over .90. Without this configured grouping, the children were unable to make a successful comparison. Experiments 2 and 3 controlled for a strategy based on non-numerical parameters (areas delimited by dots or the sum areas of dots, etc.) or use symbolic strategies. These results suggest that configured grouping enables humans to distinguish between two large exact numbers of objects, even when innate number sense and symbolic strategies are ineffective. These results are consistent with what we call “the configured group hypothesis”: configured groups play a fundamental role in the acquisition of exact numerical abilities.