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PubMed2007

The development of context sensitivity in children's graphic copying strategies.

The authors report on a series of 5 experiments in which 462 5- to 10-year-old children and 109 adults were required to copy geometric figures either with no constraints or following prior exposure to primes consisting of different parsings of the figures. The analysis focused on the graphic strategies adopted by the participants to copy the models. Three developmental steps were revealed in the baseline copying condition. Priming experiments demonstrated that the age-developmental step correspondence varied as a function of the type of prime used. However, the impact of priming differed according to age. It was limited at 6 years, whereas its size was noticeable at the other ages. These results are discussed in the light of developmental models that hypothesize a major role either for endogeneous factors in cognitive development or for exogeneous and contextual factors.

Adult↗
PubMed1995

Preemption effects in visual search: evidence for low-level grouping.

Experiments are presented showing that visual search for Mueller-Lyer stimuli is based on complete configurations rather than component segments. Segments easily detected in isolation were difficult to detect when embedded in a configuration, indicating preemption by low-level groups. This preemption--which caused stimulus components to become inaccessible to rapid search--was an all-or-nothing effect and so could serve as a powerful test of grouping. It is shown that these effects are unlikely to be due to blurring by simple spatial filters at early visual levels. It is proposed instead that they are due to more sophisticated processes that rapidly blind contour fragments into spatially extended assemblies. These results support the view that rapid visual search cannot access the primitive elements formed at the earliest stages of visual processing; rather, it can access only higher level, more ecologically relevant structures.

Attention↗
PubMed2005

Time course of linguistic information extraction from consecutive words during eye fixations in reading.

Sequential attention shift models of reading predict that an attended (typically fixated) word must be recognized before useful linguistic information can be obtained from the following (parafoveal) word. These models also predict that linguistic information is obtained from a parafoveal word immediately prior to a saccade toward it. To test these assumptions, sentences were constructed with a critical pretarget-target word sequence, and the temporal availability of the (parafoveal) target preview was manipulated while the pretarget word was fixated. Target viewing effects, examined as a function of prior target visibility, revealed that extraction of linguistic target information began 70-140 ms after the onset of pretarget viewing. Critically, acquisition of useful linguistic information from a target was not confined to the ending period of pretarget viewing. These results favor theoretical conceptions in which there is some temporal overlap in the linguistic processing of a fixated and parafoveally visible word during reading.

Attention↗
PubMed2006

Word length and lexical activation: longer is better.

Many models of spoken word recognition posit the existence of lexical and sublexical representations, with excitatory and inhibitory mechanisms used to affect the activation levels of such representations. Bottom-up evidence provides excitatory input, and inhibition from phonetically similar representations leads to lexical competition. In such a system, long words should produce stronger lexical activation than short words, for 2 reasons: Long words provide more bottom-up evidence than short words, and short words are subject to greater inhibition due to the existence of more similar words. Four experiments provide evidence for this view. In addition, reaction-time-based partitioning of the data shows that long words generate greater activation that is available both earlier and for a longer time than is the case for short words. As a result, lexical influences on phoneme identification are extremely robust for long words but are quite fragile and condition-dependent for short words. Models of word recognition must consider words of all lengths to capture the true dynamics of lexical activation.

Cognition↗
PubMed2006

Size constancy in infants: 4-month-olds' responses to physical versus retinal image size.

This study tested whether 4-month-old infants respond primarily to objects' physical or retinal image sizes. In the study's main experiment, infants were habituated to either a 6-cm-diameter disk at a distance of 18 cm or a 10-cm disk at 50 cm. They were then given 2 test trials in which the 6- and 10-cm disks were presented side by side at a distance of 30 cm. For each infant, one test object had a novel physical size but a familiar retinal image size, and the other had a familiar physical size but a novel retinal image size. The infants exhibited a significant looking preference for the object that had a novel physical size. A preliminary experiment found that 4-month-olds' looking preferences are based on novelty, not familiarity, under the conditions of this study. Given this finding, the results suggest that 4-month-old infants attend and respond primarily to physical size, not to retinal image size.

Attention↗
PubMed2005

Ordinal representation of numeric quantities by brown capuchin monkeys (Cebus apella).

Using techniques established by E. M. Brannon and H. S. Terrace (2000) with rhesus macaques (Macaca mulatta), the authors tested the ability of brown capuchins (Cebus apella) to order arrays of items ranging in quantity from 1 to 9. Three monkeys were trained on a touch screen to select the quantities 1-4 in ascending order. The monkeys exhibited successful transfer of this ability to novel representations of the quantities 1-4 and to pairs of the novel quantities 5-9. Patterns of responding with respect to numeric distance and magnitude were similar to those seen in human subjects, suggesting the use of similar psychological processes. The capuchins demonstrated an ordinal representation of quantity equivalent to that shown in Old World monkeys.

Animals↗
PubMed2004

The influence of stimulus properties on category construction.

It has been demonstrated that when people free classify stimuli presented simultaneously in an array, they have a preference to categorize by a single dimension. However, when people are encouraged to categorize items sequentially, they sort by "family resemblance," grouping by overall similarity. The present studies extended this research, producing 3 main findings. First, the sequential procedure introduced by G. Regehr and L. R. Brooks (1995) does not always produce a preference for family resemblance sorts. Second, sort strategy in a sequential procedure is sensitive to subtle variations in stimulus properties. Third, spatially separable stimuli evoked more family resemblance sons than stimuli of greater spatial integration. It is suggested that the family resemblance sorting observed is due to an analytic strategy.

Association Learning↗
PubMed2005

An exemplar account of the bow and set-size effects in absolute identification.

The extended generalized context model for response times (K. Lamberts, 2000) was designed to account for choice proportions and response times in perceptual categorization. In this article, the hypothesis that the model also offers an account of accuracy and response times in absolute identification was investigated. The model was applied to the data from 2 absolute identification experiments and provided a good account of the bow and the set-size effects in accuracy and response time data from individual participants, including the response time distributions for individual stimuli. The model applications demonstrated that exemplar-based process models offer a viable account of absolute identification data.

Adult↗
PubMed1990

Number-related discrimination and summation by squirrel monkeys (Saimiri sciureus sciureus and S. boliviensus boliviensus) on the basis of the number of sides of polygons.

In Experiment 1, with the number of sides or angles of irregular polygons as cues, programmed training, and a 90% correct criterion (36 of 40), 2 squirrel monkeys' (Saimiri sciureus sciureus and S. boliviensus boliviensus) best performances were to discriminate heptagons from octagons, a 3rd's best was hexagons from heptagons, and a 4th's best was pentagons from heptagons. In Experiment 2, on most trials 2 polygons on one or both discriminanda had to be summed to determine which discrimination had the total fewer sides. Only 1 monkey met criterion (27 of 30) on the 2 tasks, 6 vs. 8 and 7 vs. 8 sides, but the other 3 performed better than chance on the 6 vs. 8 task. We conclude that previous studies of animals' discrimination of polygons in terms of complexity were minimally relevant to this work, and counting and subitizing were rejected in favor of a prototype-matching process to explain our monkeys' performances.

Animals↗
PubMed1991

Postprandial scanning by the rat (Rattus norvegicus): the importance of eating time and an application of "warm-up" movements.

We observed the movements of rats (Rattus norvegicus) after they had eaten food pellets of various size or hardness. With rooted hindlegs, they made head scans, with vibrissae in contact with the substrate, that began over the area below where they had eaten and then expanded to include almost the entire area surrounding their body. Scanning was not contingent on the presence of dropped food. It occurred when rats ate on a screen through which any dropped crumbs could fall. It also occurred when rats were trained to find food at a location distant to where they ate. Although the duration of scanning increased in proportion to the size of food consumed, when eating time was varied, using food items of similar size but different hardness, scanning increased in proportion to eating time. Postprandial scans resemble the exploratory (warm-up) movements that bridge transitions from immobility to locomotion. We propose that a subset of the movements of warm-up are co-opted in this postprandial period. It is likely that in natural foraging situations they are useful for food searching. The results suggest that although the motor system may be conservative in the number of actions that it can produce, diversity is achieved by applying fundamental patterns to many uses.

Animals↗
PubMed1995

Behavioral responses of longtailed macaques to different cage sizes and common laboratory experiences.

The authors tested the effects of varying cage size on the behavior of 10 female and 10 male Macaca fascicularis by singly caging them for 2 weeks in each of 5 cage sizes, ranging from approximately 20% to 148% of regulation size. Behavior in the regulation cage size, a size 23% smaller, and a size 48% larger did not differ in any analysis. Locomotion was significantly less in the 2 smallest cage sizes. Abnormal behavior occurred only 5% of the time, did not increase as cage size decreased, and did not change significantly over nearly 3 years. Disruption of the normal activity budget in the laboratory environment proved to be a useful indicator of psychological well-being. Moving to a new room and, to a lesser extent, moving into a new, clean cage, regardless of size, was associated with disrupted sleep the 1st night and suppressed activity, especially self-grooming, the next day.

Adaptation, Psychological↗
PubMed2000

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.

Animals↗
PubMed2000

Summation of symbols by pigeons (Columba livia): the importance of number and mass of reward items.

In each of 3 experiments, different sets of 4 pigeons (Columba livia) were trained to discriminate between 2 visual symbols that covered wells containing food items that varied in number, mass, or both. In Experiment 1, the symbols were associated with 0, 1, 3, 5, 7, or 9 pieces of grain reward. The pigeons learned to choose the symbol corresponding to the larger reward, and on summation tests, they chose the pair of symbols that summed to the larger total reward. When number of food pellets was varied but mass of reward was held constant in Experiment 2, preference for the larger number symbols failed to appear. When number was held constant and mass was varied in Experiment 3, the pigeons showed a clear preference for the larger mass symbols on single-symbol and summation tests. These findings show that pigeons summate the value of symbols and are more likely to represent symbols by mass of food reward than by number of food items.

Animals↗
PubMed2001

Size matters: impact of item size and quantity on array choice by chimpanzees (Pan troglodytes).

The authors previously reported that chimpanzees (Pan troglodytes) showed a striking bias to select the larger of 2 candy arrays, despite a reversed reward contingency in which the animals received the smaller, nonselected array as a reward, except when Arabic numerals were used as stimuli. A perceptual or incentive-based interference occurred that was overcome by symbolic stimuli. The authors of the present study examined the impact of element size in choice arrays, using 1 to 5 large and small candies. Five test-sophisticated chimpanzees selected an array from the 2 presented during each trial. Their responses were not optimal, as animals generally selected arrays with larger total mass; thus, they received the smaller remaining array as a reward. When choice stimuli differed in size and quantity, element size was more heavily weighted, although choices reflected total candy mass. These results replicate previous findings showing chimpanzees' difficulties with quantity judgments under reverse reward contingencies and also show that individual item size exerts a more powerful interference effect.

Animals↗
PubMed2003

Differential effects of visual context on pattern discrimination by pigeons (Columba livia) and humans (Homo sapiens).

Three experiment examined the role of contextual information during line orientation and line position discriminations by pigeons (Columba livia) and humans (Homo sapiens). Experiment 1 tested pigeons' performance with these stimuli in a target localization task using texture displays. Experiments 2 and 3 tested pigeons and humans, respectively, with small and large variations of these stimuli in a same-different task. Humans showed a configural superiority effect when tested with displays constructed from large elements but not when tested with the smaller, more densely packed texture displays. The pigeons, in contrast, exhibited a configural inferiority effect when required to discriminate line orientation, regardless of stimulus size. These contrasting results suggest a species difference in the perceptionand use of features and contextual information in the discrimination of line information.

Animals↗
PubMed2005

Experience and materials affect combinatorial construction in tufted capuchin monkeys (Cebus apella).

Three movement procedures can combine nesting cups into seriated structures. Reliance on these procedures changes with age in human children, and the putatively most advanced emerges as a predominant procedure at 3 or more years. Six monkeys' (Cebus apella) combinatorial procedures and successes at nesting seriated cups were evaluated. The current study examined whether the procedures used (a) shift toward more efficient procedures after unguided experience, (b) are dependent on the type of object being combined, and (c) can be altered by specific training history. All factors produced a change in procedure for some individuals, suggesting that combinatorial procedure is a product of the dynamic influences of preexisting tendencies to act in certain ways, of environmental circumstances, and of prior experiences. Some monkeys preferred the putatively most cognitively complex procedure.

Animals↗
PubMed2005

Understanding of the concept of numerically "less" by bottlenose dolphins (Tursiops truncatus).

In 2 experiments, bottlenose dolphins (Tursiops truncatus) judged the ordinal relationship between novel numerosities. The dolphins were first trained to choose the exemplar with the fewer number of items when presented with just a few specific comparisons (e.g., 2 vs. 6, 1 vs. 3, and 3 vs. 7). Generalization of this rule was then tested by presenting the dolphins with all possible pairwise comparisons between 1 and 8. The dolphins chose the exemplar with the fewer number of items at levels far above chance, showing that they could recognize and represent numerosities on an ordinal scale. Their pattern of errors was consistent with the idea of an underlying analog magnitude representation.

Animals↗
PubMed2005

Unlearned appetite controls: watersnakes (Nerodia) take smaller meals when they have the choice.

Studies of appetite in mammals emphasize that meal size is learned, but lactation and parental care constrain testing of naive individuals. Neonatal reptiles, in contrast, are self-sufficient foragers. The authors examined the effect of prey size on meal size in primivorous (at first feeding) northern watersnakes (Nerodia sipedon). When offered an excess of small prey (2%-20% of snake mass), neonates ate significantly smaller meals (M = 23.5% of snake mass) than when offered a single huge item (range = 32%-55%). The authors conclude that (a) the taking of smaller meals is not a learned effect, (b) there may be a satiety threshold for meal size rather than a target, (c) oropharyngeal stimuli may provide satiety cues, and (d) huge meals may have fitness costs.

Age Factors↗