Influences of semantic and syntactic context on open- and closed-class words

Event-related potentials (ERPs) were recorded as subjects read semantically meaningful, syntactically legal but nonsensical and random word strings. The constraints imposed by formal sentence structure alone did not reduce the amplitude of the N400 component elicited by open-class words, whereas semantic constraints did. Semantic constraints also eliminated the word-frequency effect of a larger N400 for low-frequency words. Responses to closed-class words exhibited reduced N400 amplitudes in syntactic and congruent sentences, indicating that formal sentence structure placed greater restrictions on closed-class words than it did on open-class words. However, unlike the open-class results, the impact of sentence context on closed-class words was stable across word positions, suggesting that these syntactic constraints were applied only locally. A second ERP component, distinct from the N400, was elicited primarily by congruent closed-class words.     

False prototype enhancement effects in dot pattern categorization

Results from the classic dot pattern distortion paradigm have sometimes yielded prototype enhancement effects that could not be accounted for by exemplar models of categorization. However, in these experiments the status of the prototype was confounded with certain stimulus-specific properties as well as with the frequency of presentation of the prototype during testing. In two mock-subliminal experiments, participants made categorization judgments to patterns that were generated as prototypes, low-level distortions, or high-level distortions. The participants rated the prototypes as being more likely to be members of a category, although no patterns were presented during training, and there was no objective category structure. In two other experiments, greater prototype enhancement effects were observed when the prototype and low-level distortions were presented with greater frequency during transfer. These results suggest that classic prototype enhancement effects may not be due to the abstraction of a prototype at time of original learning, but rather to other factors not formalized in extant models.     

Monocular discrimination of rigidly and nonrigidly moving objects

Wemeasured thresholds for the monocular discrimination of rigidly and nonrigidly moving objects defined by motion parallax. The retinal projections of rigidly moving objects are subject to certain constraints. By applying smooth 2-D transformations to the projections of rigidly moving objects, we created stimuli in which these constraints were affected. Thresholds for (generic) nonrigid transformations that in theory can be detected from rigid ones by processing pairs of views depended not only on the extent to which the rigidity constraints were affected, but also on the structure and the movement of the simulated object. Nonrigid transformations under which every three successive views had a rigid interpretation were not discriminable from rigid transformations, except in cases where the distortions were very large. Under the rigidity assumption, this would mean that a large class of nonrigidly moving objects is erroneously perceived as rigidly moving.     

Capacities underlying word learning

Children are strikingly good at learning the meanings of words. Current controversy focuses on the relative importance of different capacities in this learning process including principles of association, low-level attentional mechanisms, special word learning constraints, syntactic cues and theory of mind. We argue that children succeed at word learning because they possess certain conceptual biases about the external world, the ability to infer the referential intentions of others and an appreciation of syntactic cues to word meaning. Support for this view comes from studies exploring the phenomena of fast mapping, the whole object bias, the acquisition of names for entities belonging to different ontological kinds and the effect of lexical contrast. Word learning is not the result of a general associative learning process, nor does it involve specialized constraints. The ability to learn the meanings of words depends on a number of capacities, some of which are specific to language and unique to humans, others of which are potentially shared with other species.     

Pitch direction ability predicts melodic perception in autism

Individuals with autism spectrum disorders (ASDs) often present atypical auditory perception. Previous work has reported both enhanced low-level pitch discrimination and superior abilities to detect local pitch structure on higher-level melodic tasks in ASD. However, it is unclear how low and high levels of auditory perception are related in ASD or typical development (TD), or how this relationship might change across development and stimulus presentation rates. To these aims, in the present study, children with ASD and TD were tested on a low-level pitch direction discrimination task and a high-level melodic global-local task. Groups performed similarly on both of these auditory tasks. Moreover, individual differences in low-level pitch direction ability predicted performance on the higher-level global-local task, with a stronger relationship in ASD. Age did not affect the relationship between low-level and high-level pitch performance in either ASD or TD. However, there was a more positive effect of age on the high-level global-local task performance in TD than ASD. Finally, there was no effect of stimulus rate on the relationship between low-level and high-level pitch performance in either group. These findings provide a better understanding of how perception is associated across levels of processing in ASD versus TD. This work helps to better understand individual differences in auditory perception and to refine ASD phenotypes.     

Shape constancy from novel views

Prior experiments on shape constancy from novel views are inconclusive: Some show that shapes of objects can be recognized reliably from novel views, whereas others show just the opposite. Our analysis of prior results suggests that shape constancy from novel views is reliable when the object has properties that constrain its shape: The object has volumetric primitives, it has surfaces, it is symmetrical, it is composed of geons, its contours are planar, and its images provide useful topological information about its three-dimensional structure. To test the role of some of these constraints, we performed a set of experiments. Solid shapes (polyhedra) were shown on a computer monitor by means of kinetic depth effect. Experiment 1 showed that shape constancy can be reliably achieved when a polyhedron is represented by its contours (most of the constraints are present), but not when it is represented by vertices or by a polygonal line connecting the vertices in a random order (all the constraints are absent). Experiments 2 and 3 tested the role of individual constraints. Results of these experiments show that shape constancy from novel views is reliable when the object has planar contours and when the shapes of the contours together with topological information about the relations among the contours constrain the possible interpretations of the shape. Symmetry of the object and the topological stability of its image also contribute to shape constancy.     

Using information theory to assess the diversity,complexity, and development of communicative repertoires

The application of quantitative and comparative measures from information theory on animal communication can provide novel insights into the ecological, environmental, social, and contextual properties that shape the structure, organization, and function of signal repertoires. Using 2 phylogenetically different mammalian species that share similar ecological and social constraints as examples, the authors quantitatively examined the internal structure and development of a subsystem of these species' vocal repertoires in comparison with that of human language and illustrated that these species exhibit convergent developmental processes. The authors also discussed how predictions on the structure and organization of animal communication systems can be made from this new application of information theoretic measures with respect to behavioral ecology.     

An on-line laboratory in cognition and perception

The design of a computer-based laboratory system requires the coordination of pedagogical and technical goals. The development of our on-line laboratory in cognition and perception is described. The laboratory consists of 11 on-line experiments in which the student participates as both experimenter and subject. The software was designed for maximum transportability: Programs were written in a low-level BASIC, with thorough documentation; flexibility is provided both within and across experiments to suit local constraints; and the experiments are supported by a student manual, instructor’s manual, and implementation notes. Criteria for selecting experiments, implementation of the experiments, and preliminary evaluation of the laboratory are discussed.     

The construction and initial validation of the Work Volition Scale

This study constructed an instrument measuring work volition for adult populations, defined as the perceived capacity to make occupational choices despite constraints. In Study 1, an exploratory factor analysis produced a 3-factor structure containing subscales assessing general volition, financial constraints, and structural constraints. The full Work Volition Scale (WVS) and three subscales demonstrated adequate to strong internal consistency. In Study 2, a confirmatory factor analysis replicated the factor structure from Study 1 with a new sample. The hypothesized factor structure of the WVS was a good fit to the data and was internally consistent. In Studies 2 and 3, work volition correlated in hypothesized directions with work locus of control, core self-evaluations, career barriers, career compromise, and adaptive personality traits, providing evidence of construct validity. Additionally, none of these correlations was large enough to indicate overlapping constructs. Finally, work volition added unique variance in the prediction of job satisfaction above and beyond the variance accounted for by work locus of control, core self-evaluations, and the big 5 personality traits, suggesting incremental validity of the construct. Research implications are discussed.     

Mid-level feature contributions to category-specific gaze guidance

Our research has previously shown that scene categories can be predicted from observers’ eye movements when they view photographs of real-world scenes. The time course of category predictions reveals the differential influences of bottom-up and top-down information. Here we used these known differences to determine to what extent image features at different representational levels contribute toward guiding gaze in a category-specific manner. Participants viewed grayscale photographs and line drawings of real-world scenes while their gaze was tracked. Scene categories could be predicted from fixation density at all times over a 2-s time course in both photographs and line drawings. We replicated the shape of the prediction curve found previously, with an initial steep decrease in prediction accuracy from 300 to 500 ms, representing the contribution of bottom-up information, followed by a steady increase, representing top-down knowledge of category-specific information. We then computed the low-level features (luminance contrasts and orientation statistics), mid-level features (local symmetry and contour junctions), and Deep Gaze II output from the images, and used that information as a reference in our category predictions in order to assess their respective contributions to category-specific guidance of gaze. We observed that, as expected, low-level salience contributes mostly to the initial bottom-up peak of gaze guidance. Conversely, the mid-level features that describe scene structure (i.e., local symmetry and junctions) split their contributions between bottom-up and top-down attentional guidance, with symmetry contributing to both bottom-up and top-down guidance, while junctions play a more prominent role in the top-down guidance of gaze.     

Structural constraints and object similarity in analogical mapping and inference

Theories of analogical reasoning have viewed relational structure as the dominant determinant of analogical mapping and inference, while assigning lesser importance to similarity between individual objects. An experiment is reported in which these two sources of constraints on analogy are placed in competition under conditions of high relational complexity. Results demonstrate equal importance for relational structure and object similarity, both in analogical mapping and in inference generation. The human data were successfully simulated using a computational analogy model (LISA) that treats both relational correspondences and object similarity as soft constraints that operate within a limited-capacity working memory; but not with a model (SME) that treats relational structure as pre-eminent.     

A novel paradigm reveals the role of reentrant visual processes in object substitution masking

Object substitution masking (OSM) occurs when an initial display of a target and mask continues with the mask alone, creating a mismatch between the reentrant hypothesis, triggered by the initial display, and the ongoing low-level activity. We tested the proposition that the critical factor in OSM is not whether the mask remains in view after target offset, but whether the representation of the mask is sufficiently stronger than that of the target when the reentrant signal arrives. In Experiment 1, a variable interstimulus interval (ISI) was inserted between the initial display and the mask alone. The trailing mask was presumed to selectively boost the strength of the mask representation relative to that of the target. As predicted, OSM occurred at intermediate ISIs, at which the mask was presented before the arrival of the reentrant signal, creating a mismatch, but not at long ISIs, at which a comparison between the reentrant signal and the low-level activity had already been made. Experiment 2, conducted in dark-adapted viewing, ruled out the possibility that low-level inhibitory contour interactions (metacontrast masking) had played a significant role in Experiment 1. Metacontrast masking was further ruled out in Experiment 3, in which the masking contours were reduced to four small dots. We concluded that OSM does not depend on extended presentation of the mask alone, but on a mismatch between the reentrant signals and the ongoing activity at the lower level. The present results place constraints on estimates of the timing of reentrant signals involved in OSM.     

Newborns' face recognition is based on spatial frequencies below 0.5 cycles per degree

A critical question in Cognitive Science concerns how knowledge of specific domains emerges during development. Here we examined how limitations of the visual system during the first days of life may shape subsequent development of face processing abilities. By manipulating the bands of spatial frequencies of face images, we investigated what is the nature of the visual information that newborn infants rely on to perform face recognition. Newborns were able to extract from a face the visual information lying from 0 to 1 cpd (Experiment 1), but only a narrower 0-0.5 cpd spatial frequency range was successful to accomplish face recognition (Experiment 2). These results provide the first empirical support of a low spatial frequency advantage in individual face recognition at birth and suggest that early in life low-level, non-specific perceptual constraints affect the development of the face processing system.     

Weighted constraints in generative linguistics

Harmonic Grammar (HG) and Optimality Theory (OT) are closely related formal frameworks for the study of language. In both, the structure of a given language is determined by the relative strengths of a set of constraints. They differ in how these strengths are represented: as numerical weights (HG) or as ranks (OT). Weighted constraints have advantages for the construction of accounts of language learning and other cognitive processes, partly because they allow for the adaptation of connectionist and statistical models. HG has been little studied in generative linguistics, however, largely due to influential claims that weighted constraints make incorrect predictions about the typology of natural languages, predictions that are not shared by the more popular OT. This paper makes the case that HG is in fact a promising framework for typological research, and reviews and extends the existing arguments for weighted over ranked constraints.     

Visual and acoustic information supporting a happily expressed speech-in-noise advantage

There was an advantage found for recognizing happily expressed audio and audio-visual speech-in-noise relative to speech spoken with neutral or sad expressions. The advantage of happily expressed speech was explored in a set of visual and acoustic manipulations designed to isolate the potential contributions from each signal. For this research, a replication of previous research with the happily expressed speech advantage was completed with a novel inclusion of a learning paradigm. Additional experiments directly investigated the role of the fundamental frequency of the voice for affect, and the affective facial components with the eyes and mouth. We found that the happily expressed speech advantage persisted despite constraints to the amount of frequency modulation and with distortions to the talker's face. These findings seem largely attributable to the influences of affect on low-level acoustical and articulatory information, with only a very subtle role of approach/withdrawal motivation.