Line Drawings Of Objects Research Articles

Dynamics of brain activation during an explicit word and image recognition task: an electrophysiological study.

Recent brain imaging studies suggest that semantic processing of words and images may share a common neural network, although modality-specific activation can also be observed. Other studies using event-related potentials (ERPs) report that brain responses to words and images may already differ at approximately 150 ms following stimulus presentation. The question thus remains, which differences are due to perceptual categorization processes and which differences are due to the semantic ones? Using ERP recordings and spatio-temporal source localization analysis, we investigated the dynamics of brain activation during a recognition task. The stimuli consisted of a randomized set of verbal (words vs. non-words) and pictorial items (line drawings of objects vs. scrambled drawings). After each stimulus, subjects had to decide whether it corresponds to a recognizable word or objects. ERP map series were first analyzed in terms of segments of quasi-stable map topography using a cluster analysis. This showed that verbal and pictorial stimuli elicited different field patterns in two time segments between approximately 190-400 ms. Before and after this period, map patterns were similar between verbal and pictorial conditions indicating that the same brain structures were engaged during the early and late steps of processing. Source localization analysis of map segments corresponding to the P100 and the N150 components first showed activation of posterior bilateral regions and then of left temporo-posterior areas. During the period differentiating conditions, other patterns of activation, involving mainly left anterior and posterior regions for words and bilateral posterior regions for images, were observed. These findings suggest that, while sharing an initial common network, recognition of verbal and pictorial stimuli subsequently engage different brain regions during time periods generally allocated to the semantic processing of stimuli.

Dynamics of brain activation during a word and image recognition task: An electrophysiological study

Recent brain imaging studies suggest that semantic processing of words and images may share a common neural network, although modality-specific activation can also be observed. Other studies using event-related potentials (ERPs) report that brain responses to words and images may already differ at ~150 ms following stimulus presentation. The question thus remains, which differences are due to perceptual categorization processes and which differences are due to the semantic ones? Using ERP recordings and spatio-temporal source localization analysis, we investigated the dynamics of brain activation during a recognition task. The stimuli consisted of a randomized set of verbal (words vs. non-words) and pictorial items (line drawings of objects vs. scrambled drawings). After each stimulus, subjects had to decide whether it corresponds to a recognizable word or objects. ERP map series were first analyzed in terms of segments of quasi-stable map topography using a cluster analysis. This showed that verbal and pictorial stimuli elicited different field patterns in two time segments between ~190-400 ms. Before and after this period, map patterns were similar between verbal and pictorial conditions indicating that the same brain structures were engaged during the early and late steps of processing. Source localization analysis of map segments corresponding to the P100 and the N150 components first showed activation of posterior bilateral regions and then of left temporo-posterior areas. During the period differentiating conditions, other patterns of activation, involving mainly left anterior and posterior regions for words and bilateral posterior regions for images, were observed. These findings suggest that, while sharing an initial common network, recognition of verbal and pictorial stimuli subsequently engage different brain regions during time periods generally allocated to the semantic processing of stimuli.

Category effects on the processing of plane-rotated objects.

We examined the effects of plane rotations on the identification of exemplars of three semantic categories. In the first two experiments line drawings belonging to three categories (animals, inanimate objects, and vegetables) were presented at four orientations (0 degree, 60 degrees, 120 degrees, and 180 degrees of clockwise rotation). The response time was found to depend on stimulus category. In particular, whereas rotation effects were shown for animals, no effect at all was found for vegetables and only partial effects were found for inanimate objects. The unclear pattern found for inanimate objects was further examined in experiment 3 where the orientation effects on the identification of two subsets of the inanimate category were studied. The hypothesis of view-observation frequency was confirmed. In experiment 4, line drawings of objects at different orientations were presented in physically degraded versions. The minimum amount of visual information necessary to identify rotated stimuli was found to vary as a function of stimulus category as well. Results are discussed, combining current research on both viewpoint-dependence/independence and neural systems involved in category processing.

Last in, First to Go: Age of Acquisition and Naming in the Elderly

Twenty-six elderly subjects (ages 71–86) and 10 young adult subjects (ages 22–33) named 206 black-and-white line drawings of objects. Although the two groups did not differ significantly on VIQ, the elderly group named significantly fewer of the objects than the younger group (who were almost at ceiling). A regression analysis of the data from the elderly group found effects of both age of acquisition and name agreement on naming accuracy after 5 and 15 s and an effect of word length after 5 but not 15 s. There were no independent effects of picture complexity, object familiarity, word frequency, or imageability. The majority of the elderly subjects' naming errors were semantic in nature, with circumlocutions, visual errors, and “don't know” responses accounting for most of the remaining errors. The implications of the findings for our understanding of word-finding problems in the elderly are discussed.

Effects of orientation on the identification of rotated objects depend on the level of identity.

Matching names and rotated line drawings of objects showed effects of object orientation that depended on name level. Large effects, in the same range as object naming, were found for rotations between 0 degrees and 120 degrees from upright with subordinate names (e.g., collie), whereas nonsignificant effects were found with superordinate (e.g., animal) and basic names (e.g., dog). These results support image normalization, after contact with orientation-invariant representations, that provide basic-level identity. They consequently fail to support theories of object recognition in which rotated object images are normalized to the upright position before contact with long-term object representations.

Contrast and illumination effects on explicit and implicit measures of memory.

The present study examined the effect of changing the contrast polarity and illumination of objects on explicit (episodic recognition) and implicit (fragment naming or object-nonobject decision) memory tasks. Changes in contrast polarity of line drawings of objects did not affect priming on fragment naming or on object-nonobject decision tasks but adversely affected recognition judgments. Similarly, changes in illumination did not affect priming on the object-nonobject decision task but adversely affected recognition memory. Together, the results suggest that implicit measures tap abstract descriptions of object structure useful for the purposes of object identification, whereas recognition memory taps descriptions that integrate shape information with lower level perceptual information. It is argued that lower level perceptual information influences episodic recognition because it provides a cue to the spatiotemporal context within which the prior encounter with the object occurred.

Unilateral Neglect can be Affected by Stimuli in the Neglected Field

Neglect, patients' attention is usually pathologically captured by stimuli present on the side ipsilateral to the brain damage. In previous research it was. shown that'. not only the mere presence but also the number of “relevant” stimuli on the right side. influenced patient's performance. However, the influence of stimuli whose presence: was. completely irrelevant for the execution of the task was not previously studied.We asked neglect patients to bisect lines of 28 cm of length, which could be presented alone or with line-drawings of objects placed either only on the left, only on the right or bilaterally on the display. We found that, the presence of irrelevant .left-side stimuli improved the bisection performance in 3 out of 5 patients with respect to the baseline condition, in which no stimuli were present on either side of the display. Right-side stimuli did not affect the performance, whereas bilateral stimuli tended to worsen the performance for those patients who presented the beneficial effect of left-side stimuli. These findings were discussed with reference to the hypotheses advanced to explain neglect.

Reference frame and effects of orientation on finding the tops of rotated objects.

Effects of stimulus orientation across trial blocks and the spatial reference frame were investigated with a task in which Ss, with their head upright or tilted, judged a dot to be near the top or the bottom of rotated line drawings of objects. Objects used in this task were also named. Response times from the first block of trials increased linearly for objects rotated from 0 degrees to 120 degrees from the upright. Across blocks, orientation effects diminished for naming but remained the same for top-bottom discriminations. Practice with top-bottom discriminations diminished orientation effects when the same objects were subsequently named. The spatial reference frame for top-bottom discriminations was midway between retinal and environmental coordinates. Specifying the location of object features is of greater importance for top-bottom discriminations than for naming and underlies orientation effects in these tasks.

Model-Constrained Recognition Of Line Drawings Of Objects By Production Rules And Hierarchical Structures

A model-constrained rule-based object recognition system for line drawings is considered. The system is composed of three subsystems: preprocessing (segmentation), feature extraction, and pattern matching. The subsystems and the processes within each system are arranged in a hierarchical structure. The actual implementation is centered around the ideas of view-angle-independent object recognition and robustness with incomplete or noisy line drawings of objects. The line drawing of a scene containing simple objects is first segmented into independent objects using a set of heuristics stored in the knowledge base. The segmented object is then mapped into a newly devised structural-symbolic representation that is independent of small view-angle changes. Large view-angle independence is achieved by multiple models for the same object. Incomplete line drawings and noisy line drawings are detected and modified by the preprocessing module before being presented to the pattern matcher. The matching process is carried out by production rule inferencing. The system implemented has the characteristics of being flexible and easy to modify. These advantages are rooted in the utilization of the rule-based approach. A test of the system has been carried out, with a satisfactory result.

The Influence of Verbal Descriptions versus Orientation Codes on Kindergartners' Memory for the Orientation of Pictures

Kindergarten children who viewed a series of 10 line drawings of objects subsequently showed little ability to distinguish between these pictures and their left-right mirror images. However, the children's memory for orientation improved substantially when children were induced to (a) give detailed verbal descriptions of the pictures, or (b) specify a difference between characteristics on the child's side versus the experimenter's side of each picture, or (c) both. The 3 induced strategies were equally effective. On a posttest given approximately a week later, the children did not maintain use of any of these effective strategies.

Redundancy in line drawings of familiar objects: Effects of age and intelligence

At optimum performance, line drawings of objects are approximately 50% redundant, as measured by the recognition levels maintained after varying percentages of lines have been deleted. Discriminative redundancy increases sharply up to age 8 yr, then gradually into adulthood, and is unaffected by mild mental retardation. We infer that, with increasing age, more aspects of familiar objects are converted into distinctive features.