A Redefinition of Odor Mixture Quality.

Odor mixtures are perceived as different from (configural) or the same as (elemental) their components. Recent studies (L. M. Kay, C. A. Lowry, & H. A. Jacobs, 2003; C. Wiltrout, S. Dogra, & C. Linster, 2003) propose that component structural or perceptual similarities predict configural properties of binary mixtures. The authors evaluated this in rats using 4 binary mixtures with varying structural similarity (eucalyptol-benzaldehyde, eugenol-benzaldehyde, octanol-octanal, and [+/-]-limonene). The range of tested ratios for each mixture was determined by the components' vapor pressures. Three results are presented: (a) No mixture maintains purely elemental or configural properties for all concentration ratios, (b) structural similarity or dissimilarity does not predict configural or elemental perception, and (c) overshadowing is significant in responses to all odor sets. The authors offer more precise definitions of elemental and configural properties and overshadowing as they relate to odor mixture perception. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Receptor contributions to configural and elemental odor mixture perception.

Odor mixture perception can be configural (the mixture is qualitatively different from the components) or elemental (the components are recognizable). Some have argued that configural properties are dependent on chemical similarity and possible overlap at the receptor level. The authors show that a binary mixture in which both components activate the same receptor (17) has a configural odor, whereas a mixture that suppresses overlap has elemental odor properties. Rats trained to recognize mixtures of citronellal and octanal (strong 17 agonists) in many ratios rarely recognize the components, supporting configural representation of the odor mixture. However, when trained to recognize mixtures of citral (partial 17 agonist, inhibitor) and octanal, rats recognize 1 or both components over a wide range of ratios. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A critical test of the overlap hypothesis for odor mixture perception.

The overlap hypothesis of mixture perception is based on the observation that mixtures of perceptually similar odorants tend to smell different from their components (configural), whereas mixtures of dissimilar odorants smell like their components (elemental). Because input patterns of perceptually similar odorants tend to overlap more than dissimilar ones, it has been hypothesized that component pattern overlap can predict a mixture's perceptual quality, with high overlap predicting a configural response and low overlap an elemental response. The authors used 7 pairs of odorants chosen for different degrees of overlap in their monomolecular 2-deoxyglucose activation patterns to test the theory in a go/no-go behavioral assay that measured generalization from binary mixtures to components. The authors show that individual component odorant input patterns are not sufficient to predict mixture quality, falsifying the overlap hypothesis. An important finding is that different odorant pairs with similar glomerular overlap showed opposite behavioral–perceptual responses, suggesting nonlinear effects at the receptor or glomerular level or the critical involvement of higher order areas. Thus, the authors posit that imaging the mixtures themselves may provide additional information needed to reliably predict mixture quality. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Binary mixture perception is affected by concentration of odor components.

Some controversy still exists as to how binary odorant mixtures are behaviorally perceived, despite many studies aimed at understanding this phenomenon. Binary mixture perception by rodents is a first step in elucidating how more complex odor blends may be perceived. Research thus far has examined how the degree of component similarity, olfactory receptor overlap, relative concentration of components, and even olfactory enrichment affect the behavioral perception of binary mixtures. These studies have aimed to categorize binary mixtures into 1 of 3 rigid categories, but often the results conflict as to which category a particular mixture belongs. In the present article, the authors used a habituation/discrimination paradigm to determine whether rats' perception of one component of a binary mixture of either perceptually similar or dissimilar components changed when the concentration of both components was varied together. The authors found that perception of a binary mixture changed with changing component concentration, such that one binary mixture could be categorized differently depending on component intensity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Selective loss of cholinergic neurons projecting to the olfactory system increases perceptual generalization between similar, but not dissimilar, odorants.

The neuromodulator acetylcholine is thought to modulate information processing in the olfactory system. The authors used 192 IgG-saporin, a lesioning agent selective for basal forebrain cholinergic neurons, to determine whether selective lesions of cholinergic neurons projecting to the olfactory bulb and cortex affect odor perception in rats. Lesioned and sham-operated rats were tested in an olfactory generalization paradigm with sets of chemically related odorants (n-aliphatic aldehydes, acids, and alcohols). Lesioned rats generalized more between chemically similar odorants but did not differ from controls in their response to chemically unrelated odorants or in acquisition of the conditioned odor. Results show that cholinergic inputs to the olfactory system influence perceptual qualities of odorants and confirm predictions made by computational models of this system. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dependence on external influence: Correlates in perception, attitudes, and judgment.

The hypothesis that people have a generalized tendency to accept or reject external influence is tested in perceptual and conformity situations, using 53 college males as S's. The results show that S's who are highly influenced by the field in one perceptual test perform similarly in other perceptual tests, conformity measures are not significantly interrelated, and field dependent perceptual behavior is associated with high conformity in other tests, particularly autokinetic and attitude change measures. It is suggested that while perceptual performance reflects central tendencies of the person, his performance in specific conformity situations is subject to greater fluctuation as a result of more peripheral factors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The bounds on flexibility in speech perception.

Dutch listeners were exposed to the English theta sound (as in bath), which replaced [f] in /f/-final Dutch words or, for another group, [s] in /s/-final words. A subsequent identity-priming task showed that participants had learned to interpret theta as, respectively, /f/ or /s/. Priming effects were equally strong when the exposure sound was an ambiguous [fs]-mixture and when primes contained unambiguous fricatives. When the exposure sound was signal-correlated noise, listeners interpreted it as the spectrally similar /f/, irrespective of lexical bias during exposure. Perceptual learning about speech is thus constrained by spectral similarity between the input and established phonological categories, but within those limits, adjustments are thorough enough that even nonnative sounds can be treated fully as native sounds. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Top-down contingencies in peripheral cuing: The roles of color and location.

According to contingent-processing accounts, peripheral cuing effects are due to the cues' inadvertent selection for processing by control settings set up for targets (e.g., C. L. Folk, R. W. Remington, & J. C. Johnston, 1992). Consequently, cues similar to targets should have stronger effects than do dissimilar cues. In the current study, this prediction is confirmed for cue-target combinations similar or dissimilar in the static features of color (Experiments 1-3) and location (Experiment 4), even when both cues and targets share the dynamic feature of abrupt onset. Perceptual priming (Experiment 2) and reallocation of attention did not account for similar-dissimilar differences (Experiments 3 and 4). The results are best explained by top-down-contingent attentional effects of the similar cues. Implications for bottom-up accounts of peripheral cuing effects are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perspective taking promotes action understanding and learning.

[Retraction Notice: A retraction for this article was reported in Vol 34(5) of Journal of Experimental Psychology: Human Perception and Performance (see record 2008-13337-018). All authors retract this article. Co-author Tversky and co-author Hard believe that the research results cannot be relied upon; Sandra C. Lozano takes full responsibility for the need to retract this article.] People often learn actions by watching others. The authors propose and test the hypothesis that perspective taking promotes encoding a hierarchical representation of an actor's goals and subgoals-a key process for observational learning. Observers segmented videos of an object assembly task into coarse and fine action units. They described what happened in each unit from either the actor's, their own, or another observer's perspective and later performed the assembly task themselves. Participants who described the task from the actor's perspective encoded actions more hierarchically during observation and learned the task better. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Behavioral models of odor similarity.

Carbon chain length in several classes of straight-chain aliphatic odorants has been proposed as a model axis of similarity for olfactory research, on the basis of successes of studies in insect and vertebrate species. To assess the influence of task on measured perceptual similarities among odorants and to demonstrate that the systematic similarities observed within homologous odorant series are not task specific, the authors compare 3 different behavioral paradigms for rats (olfactory habituation, generalization, and discrimination). Although overall patterns of odorant similarity are consistent across all 3 of these paradigms, both quantitative measurements of perceptual similarity and comparability with 2-deoxyglucose imaging data from the olfactory bulb are dependent on the specific behavioral tasks used. Thus, behavioral indices of perceptual similarity are affected by task parameters such as learning and reward associations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Odorant identification and quality perception following methyl bromide-induced lesions of the olfactory epithelium.

Using a 5-odorant identification confusion matrix task, the authors assessed the consequence of olfactory epithelial damage on odorant quality perception in the rat. After establishing prelesion identification performance, each rat's epithelium was subjected to 330 ppm methyl bromide gas for 6 hr. Comparison of prelesion and 3-day postlesion performance demonstrated a significant decrease in identification as a consequence of 95%-98% epithelial destruction. Further, there was a differential effect of lesion on the ability of different animals to identify the different individual odorants. Evaluation of the anatomical state of the epithelium relative to performance on the identification task demonstrated a significant relationship between the extent and location of anatomical sparing and changes in individual odorant identifications. Assessment of pre- and postlesion quality perception for the individual rats demonstrated a highly significant shift in quality perception that was independent of any decrease in performance. These results provide strong support for the proposition that the regional variations in mucosal sensitivities within and across olfactory receptor gene expression zones are fundamentally important for the encoding of odorant quality. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

在强加来流作用下二元系中枝晶生长的稳态解

研究了远场来流作用下二元系中的枝晶生长.当Schmidt数很大时,应用渐近分析方法得到枝晶稳态生长的渐近解,其温度场和浓度场的首级解、一级解均为相似性解,枝晶形状为存在细微波动的旋转抛物面.远场来流的强弱影响着枝晶生长的Peclet数的大小,进而影响着枝晶的尖端半径与生长速度.当过冷度一定时,在枝晶尖端或在枝晶前沿处的温度随着流场的增大而减小,而溶质浓度随着流场的增大而增大.     

"Perspective-taking promotes action understanding and learning": Retraction.

Reports a retraction of "Perspective taking promotes action understanding and learning" by Sandra C. Lozano, Bridgette Martin Hard and Barbara Tversky (Journal of Experimental Psychology: Human Perception and Performance, 2006[Dec], Vol 32[6], 1405-1421). All authors retract this article. Co-author Tversky and co-author Hard believe that the research results cannot be relied upon; Sandra C. Lozano takes full responsibility for the need to retract this article. (The following abstract of the original article appeared in record 2006-22004-008.) People often learn actions by watching others. The authors propose and test the hypothesis that perspective taking promotes encoding a hierarchical representation of an actor's goals and subgoals-a key process for observational learning. Observers segmented videos of an object assembly task into coarse and fine action units. They described what happened in each unit from either the actor's, their own, or another observer's perspective and later performed the assembly task themselves. Participants who described the task from the actor's perspective encoded actions more hierarchically during observation and learned the task better. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Personality, perceptual defense, and stereoscopic perception.

Stereoscopic perception was investigated using an experimental design similar to those employed in tachistoscopic studies of perceptual defense. "In the first experiment, some of the variables involved in stereoscopic suppression were investigated, while the second experiment demonstrated the differences in the stereoscopic perception of normals and schizophrenics." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Meaning dimensions and male-female voice perception in schizophrenics with good and poor premorbid adjustment.

This study explored certain aspects of perceptual distortion in schizophrenia. Among schizophrenics with a good premorbid adjustment, schizophrenics with a poor premorbid adjustment, and normals, auditory perception of spoken material was compared as a function of (a) sex of voice and (b) dimensions of meaning. The Ss listened to successive presentations of a recorded spoken word, mixed with decreasing amounts of masking noise, until their recognition threshold were established. Schizophrenics with poor premorbid adjustment responding to the female voice had significantly higher thresholds than those responding to the male voice. This finding did not occur in schizophrenics with good premorbid adjustment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Aging and the perceptual organization of 3-D scenes.

In the current study, the authors investigated whether the ground dominance effect (the use of ground surface information for the perceptual organization of scenes) varied with age. In Experiment 1, a scene containing a ground, a ceiling, and 2 vertical posts was presented. The scene was either in its normal orientation or rotated to the side. In Experiment 2, a blue dot was attached to each post, with location varied from bottom to top of the posts. In Experiment 3, a scene similar to that in Experiment 1 was presented in different locations in visual field. Observers judged which of the 2 objects (posts in Experiments 1 and 3, blue dots in Experiment 2) appeared to be closer. The results indicated that both younger (mean age = 22 years) and older observers (mean age = 73 years) responded consistently with the ground dominance effect. However, the magnitude of the effect decreased for older observers. These results suggest a decreased use of ground surface information by older observers for the perceptual organization of scene layout. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Infants’ intermodal perception of canine (Canis familairis) facial expressions and vocalizations.

From birth, human infants are able to perceive a wide range of intersensory relationships. The current experiment examined whether infants between 6 months and 24 months old perceive the intermodal relationship between aggressive and nonaggressive canine vocalizations (i.e., barks) and appropriate canine facial expressions. Infants simultaneously viewed static aggressive and nonaggressive expressions of the same canine and heard an aggressive or nonaggressive bark. Results indicate that 6-month-olds perceived the intermodal relationship for aggressive and nonaggressive barks and the appropriate expression. Results also revealed that in older but not younger infants, the initial or first looks were directed toward the appropriate expression and that older infants also looked proportionately longer to the incongruent expression during the latter half of the test trials. Findings are discussed in terms of perceptual narrowing and the effects of familiarity and experience. (PsycINFO Database Record (c) 2010 APA, all rights reserved)