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Test Trials (test + trials)

Distribution by Scientific Domains

Medical Sciences	55%
Psychology	33%

Selected Abstracts

Multicentre study of fragrance allergy in Hungary

CONTACT DERMATITIS, Issue 6 2002
Immediate, late type reactions
The authors followed the frequency of fragrance contact sensitization in Hungary in a multicentre study in the years 1998 and 1999. A total of 3604 patients were tested with fragrance mix (FM), and positive reactions were observed in 294 (8.2%). In 160 FM hypersensitive patients, the study was continued with patch testing of the mix constituents (cinnamic alcohol, cinnamic aldehyde, eugenol, amyl cinnamic aldehyde, hydroxycitronellal, geraniol, isoeugenol, oak moss absolute). Of the patients tested, 70.6% produced positive reactions to the constituents. FM contact sensitization was mainly observed in female patients (74.4%). The incidence of contact urticaria in FM hypersensitive patients was 6.1%. Simultaneous patch test trials of other environmental contact allergens, in both early and late evaluations, mainly confirmed hypersensitivity reactions to balsams. Female dominance of hypersensitivity reactions observed during testing the individual components of the mix was striking (82.4%). In positive skin reactions, cinnamic alcohol, isoeugenol and oak moss provoked skin symptoms most frequently. We also tested the 104 patients who produced negative reactions to FM with the constituent individual allergens, with 11.9% positive incidence. The clinical symptoms of the patients were above all manifest in the form of contact eczema, located on the hands, face, eyelids and axillae. With this study, the authors, members of the Hungarian Contact Dermatitis Research Group, call attention to one of the most frequent allergens in the environment. [source]

Sequence learning in infancy: the independent contributions of conditional probability and pair frequency information

DEVELOPMENTAL SCIENCE, Issue 6 2009
Stuart Marcovitch
The ability to perceive sequences is fundamental to cognition. Previous studies have shown that infants can learn visual sequences as early as 2 months of age and it has been suggested that this ability is mediated by sensitivity to conditional probability information. Typically, conditional probability information has covaried with frequency information in these studies, raising the possibility that each type of information may have contributed independently to sequence learning. The current study explicitly investigated the independent contribution of each type of information. We habituated 2.5-, 4.5-, and 8.5-month-old infants to a sequence of looming visual shapes whose ordering was defined independently by specific conditional probability relations among pair elements and by the frequency of occurrence of such pairs. During test trials, we tested infants' sensitivity to each type of information and found that both types of information independently influenced sequence learning by 4.5 months of age. [source]

Individuation of pairs of objects in infancy

DEVELOPMENTAL SCIENCE, Issue 4 2007
Alan M. Leslie
Looking-time studies examined whether 11-month-old infants can individuate two pairs of objects using only shape information. In order to test individuation, the object pairs were presented sequentially. Infants were familiarized either with the sequential pairs, disk-triangle/disk-triangle (XY/XY), whose shapes differed within but not across pairs, or with the sequential pairs, disk-disk/triangle-triangle (XX/YY), whose shapes differed across but not within pairs. The XY/XY presentation looked to adults like a single pair of objects presented repeatedly, whereas the XX/YY presentation looked like different pairs of objects. Following familiarization to these displays, infants were given a series of test trials in which the screen was removed, revealing two pairs of objects in one of two outcomes, XYXY or XXYY. On the first test trial, infants familiarized with the identical pairs (XY/XY) apparently expected a single pair to be revealed because they looked longer than infants familiarized with the distinct pairs (XX/YY). Infants who had seen the distinct pairs apparently expected a double pair outcome. A second experiment showed outcomes of a single XY pair. This outcome is unexpected for XX/YY-familiarized infants but expected for XY/XY-familiarized infants, the reverse of Experiment 1. This time looking times were longer for XX/YY infants. Eleven-month-olds appear to be able to represent not just individual objects but also pairs of objects. These results suggest that if they can group the objects into sets, infants may be able to track more objects than their numerosity limit or available working memory slots would normally allow. We suggest possible small exact numerosity representations that would allow tracking of such sets. [source]

Individual Odour Similarity and Discrimination in the Coruro (Spalacopus cyanus, Octodontidae)

ETHOLOGY, Issue 6 2006
Petra Hagemeyer
Previous studies of subterranean, fossorial and above-ground rodents have demonstrated that similarities in individual odours covary with genetic similarities thus supporting the theory of odour-genes covariance (i.e. the closer the individuals are genetically, the greater the similarities between their odours). We used the habituation-generalization paradigm, where the subject is exposed to the same odour stimulus in three consecutive habituation trials followed by two test trials in which the odour from two other individuals are presented successively. Using this test design, we showed that the socially living coruros (Spalacopus cyanus) discriminate individuals on the basis of their ano-genital odours and also respond to odour similarities between individuals. Male and female subjects treated ano-genital odours of two same-sex family members and also the odours of two sibling strangers as different to each other. At the same time, they treated the odours of siblings as similar compared with the odour of an unrelated individual. No gender differences were detected. Our results contrast with those from other rodent species that did not spontaneously discriminate between individual odours of siblings from a different family than their own. The polygyneous lifestyle may provide the selective background for that difference. Additional research will be necessary to explore this hypothesis and to rule out differences due to dietary preferences and due to the type of paradigm chosen for the tests. [source]

Spatiotemporal Regularity and Interevent Contingencies as Information for Infants' Visual Expectations

INFANCY, Issue 3 2002
Naomi Wentworth
This study examined infants' use of picture-location contingencies and spatiotemporal regularity in forming visual expectations. Ninety-six 3-month-olds watched an event sequence in which pictures appeared at 3 locations, either in regular left-center-right alternation or in a random center-side pattern. For half of the infants, the content of the central picture was predictive of the location of the upcoming peripheral event. Analyses of anticipations and interpicture fixation shifts revealed that both spatiotemporal regularity and consistent interevent contingencies fostered increased anticipation of peripheral pictures. The type of spatiotemporal sequence that infants observed also differentially biased their responses to test trials that followed the picture sequence: Infants who experienced regular alternation sequences continued the side-to-side pattern during the 2-choice test trials, whereas infants who experienced irregular sequences looked back to the location of the previous picture. Stable interevent contingencies, in contrast, did not bias infants' responses toward the contingent side during the choice test trials. [source]

Young Infants' Performance in the Object-Variation Version of the Above-Below Categorization Task: A Result of Perceptual Distraction or Conceptual Limitation?

INFANCY, Issue 3 2002
Paul C. Quinn
Five experiments were conducted to examine the performance of young infants on above versus below categorization tasks. Experiments 1 and 2 showed that infants did not form abstract categorical representations for above and below when familiarized with different objects depicted in a constant spatial relation relative to a horizontal bar and tested on a novel object depicted in the familiar and novel spatial relation. Experiments 3 through 5 examined perceptual-attentional distraction versus conceptually based generalization explanations for young infant performance in the object-variation version of the above-below categorization task. Experiments 3 and 4 demonstrated that infants still did not form abstract categorical representations for above and below when object variation was removed from the familiarization trials or when object novelty was reduced during the preference test trials. However, Experiment 5 showed that 3- and 4-month-olds succeeded on the above versus below categorization task when familiarized with object variation and preference tested with a familiar versus novel object-bar relation. These results indicate that young infants can form categorical representations for above and below in the object-variation version of the above-below categorization task, but that such representations are specific to the particular objects presented. Young infant performance in the object-variation version of the above-below categorization task thus reflects a conceptually based generalization limit rather than a problem of perceptual-attentional distraction. [source]

Infants' Looking at Possible and Impossible Screen Rotations: The Role of Familiarization

INFANCY, Issue 4 2000
Thomas H. Schilling
The effects of familiarization and age were examined using Baillargeon's rotating screen paradigm. In Condition A, 4-month-olds exposed to 7 180° familiarization trials looked significantly longer at the 180° test events than the 112° test events; there was a familiarity preference. In Condition B, which consisted of 12 instead of 7 180° familiarization trials, the 4-month-olds looked significantly longer at the 112° test events than the 180° test events; there was a novelty preference. In Condition C, which was similar to Condition A except that there were 112° familiarization trials, the infants showed a familiarity preference. Thus, 4-month-olds experiencing 7 familiarization trials exhibited a familiarity preference, and those experiencing 12 familiarization trials showed a novelty preference. In Condition D, 6-month-olds experienced 7 180° familiarization trials; there was no preferential looking to either familiar (180°) test events or novel (112°) test events. Therefore, looking behavior during the test trials was a function of the type of familiarization experience and age and not necessarily an inferred violation of physics. [source]

Evidence for Knowledge,Based Category Discrimination in Infancy

CHILD DEVELOPMENT, Issue 4 2002
Sabina Pauen
Two studies examined whether infants' category discrimination in an object,examination task was based solely on an ad hoc analysis of perceptual similarities among the experimental stimuli. In Experiment 1A, 11,month,olds examined four different exemplars of one superordinate category (animals or furniture) twice, followed by a new exemplar of the familiar category and an exemplar of the contrasting category. Group A (N= 39) explored natural,looking toy replicas with low between,category similarity, whereas group B (N= 40) explored artificial,looking toy models with high between,category similarity. Experiment 1B (N= 40) tested a group of 10,month,olds with the same design. Experiment 1C (N= 20) reversed the order of test trials. For Experiment 2 (N= 20), the same artificial,looking toy animals as in Experiment 1 (group B) were used for familiarization), but no category change was introduced at the end of the session. Infants' responses varied systematically only with the presence of a category change, and not with the degree of between,category similarity. This supports the hypothesis that performance was knowledge based. [source]