Attentional deficits in head-injured children: An information processing analysis

Attentional problems of closed head-injured (CHI) children were examined using an information processing (IP) approach. Based on Sternberg's (1969) additive factor method (AFM), the study examined attentional processes in terms of four stages and their corresponding task variables. A visual-spatial choice reaction-time task was undertaken with two groups of CHI children (severe and mild to moderate) and corresponding matched control groups. Results indicated that for this task both the CHI and the normal children exhibited a similar mode of linear, sequential information processing. It was found that the severe group was impaired not only in terms of slowed motor execution but also in terms of response selection. This group showed no impairment on the feature extraction, stimulus identification, and motor adjustment stages of processing. No evidence of impairment on any of the stages was found for the mild group. The utility of the AFM and implications of these findings are discussed with reference to CHI children and to neuropsychological assessment and rehabilitation.     

Measuring the stop point of rapid smoking

A method and an apparatus are described for measuring the point at which subjects elect to stop smoking when cigarette smoke is delivered more rapidly than in typical smoking. The device allows either the subject or the experimenter to control the volume of smoke and the interval between puffs. The device delivers reliable quantities of particulate matter from cigarette smoke. Subjects retested a week apart exhibited consistent stopping points.     

The role of working memory capacity and knowledge access in text inference processing

Individual differences in drawing bridging inferences during text comprehension were examined. We measured reader differences in working memory capacity, using the reading span task, and in access to relevant knowledge, using Potts and Peterson’s (1985) integration task. The dependent measure of greatest concern was answer time about facts posited to validate the bridging inference. Reading span and access were negligibly correlated, an outcome that supports their independence. Answer times were lower both for high reading span and high-access readers. In addition, readers who were either high on both reader traits or low on both traits exhibited qualitatively different inference effects from the typical pattern. It is proposed that knowledge access during comprehension is facilitated by the extraction of integrated situation models from text and that it is individuals with efficient reading processes who can construct these models.     

Prosodic form and parsing commitments

This paper examines the question of whether there are effects of prosody on the syntactic parsing of temporarily ambiguous sentences containing complement verbs. It reports the results of five experiments employing cross-modal response tasks where the visually presented target word was either an appropriate or an inappropriate continuation in terms of the prosodic form of the preceeding auditory sentence fragment. Two experiments employing cross-modal naming only showed indications of sensitivity to syntactic and appropriateness manipulations when coupled with a simultaneous appropriateness judgment task. In contrast, the experiments employing cross-modal lexical decision showed greater sensitivity to syntactic and appropriateness effects. However, while the results from these studies replicated our earlier auditory parsing results and provided support for the suggestion that there are differences in visual and auditory parsing processes and for a constituent-based, minimal commitment type auditory parser, none of the studies demonstrated an effect of prosodic form on the parsing process.     

Imagining and naming rotated natural objects

The present experiment examined whether subjects can form and store imagined objects in various orientations. Subjects in a training phase named line drawings of natural objects shown at six orientations, named objects shown upright, or imagined upright objects at six orientations. Time to imagine an upright object at another orientation increased the farther the designated orientation was from the upright, with faster image formation times at 180° than at 120°. Similar systematic patterns of effects of orientation on identification time were found for rotated objects. During the test phase, all subjects named the previously experienced objects as well as new objects, at six orientations. The orientation effect for old objects seen previously in a variety of orientations was much reduced relative to the orientation effect for new objects. In contrast, substantial effects of orientation on naming time were observed for old objects for subjects who had previously seen the objects upright only or upright but imagined at different orientations. The results suggest that the attenuation of initially large effects of orientation with practice cannot be due to imagining and forming representations of objects at a number of orientations.     

Object Recognition Difficulty in Visual Apperceptive Agnosia

Two patients with visual apperceptive agnosia were examined on tasks assessing the appreciation of visual material. Elementary visual functioning was relatively preserved, but they had profound difficulty recognizing and naming line drawings. More detailed evaluation revealed accurate recognition of regular geometric shapes and colors, but performance deteriorated when the shapes were made more complex visually, when multiple-choice arrays contained larger numbers of simple targets and foils, and when a mental manipulation such as a rotation was required. The recognition of letters and words was similarly compromised. Naming, recognition, and anomaly judgments of colored pictures and real objects were more accurate than similar decisions involving black-and-white line drawings. Visual imagery for shapes, letters, and objects appeared to be more accurate than visual perception of the same materials. We hypothesize that object recognition difficulty in visual apperceptive agnosia is due to two related factors: the impaired appreciation of the visual perceptual features that constitute objects, and a limitation in the cognitive resources that are available for processing demanding material within the visual modality.     

The Effects of Feature Identity in Operant Serial Feature-Negative Discriminations

The effects of feature identity in an operant serial feature-negative discrimination (F1 T1−, T1+) were examined in two experiments with rats. In Experiment 1, rats were trained with two operant serial feature-negative discriminations in which different operants were reinforced during two auditory target cues (T1 and T2). The features (F1 and F2) were two neutral cues (visual or auditory stimuli), two motivationally significant cues (flavored sucrose solutions, also used as the operant reinforcers), or one neutral and one motivationally significant cue. Experiment 1 showed that discrimination acquisition, transfer performance, and feature–target interval testing were facilitated with a flavored sucrose feature. Experiment 2 showed that flavored sucrose-alone presentations, more than flavored sucrose trained in a pseudodiscrimination (F1 T1+, T1+), shared several similarities with a standard flavored sucrose feature. The results suggest flavored sucrose rapidly acquires inhibitory properties, which facilitates operant serial feature-negative discrimination performance.     

Flipping and spinning: Spatial transformation procedures in the identification of rotated natural objects

The proposal that identification of inverted objects is accomplished by either a relatively slow rotation in the picture plane or a faster rotation in the depth plane about the horizontal axis was tested. In Experiment 1, subjects decided whether objects at 0° or 180° corresponded to previously learned normal views of the upright objects, or were mirror images. Instructions to mentally flip an inverted object in the depth plane to the upright produced faster decision times than did instructions to mentally spin the object in the picture plane. In Experiment 2, the effects of orientation were compared across an object-naming task and a normal-mirror task for six orientations from 0° to 300°. In the normal-mirror task, objects at 180° were cued for rotation in the picture plane or in the depth plane in equal numbers. The naming function for one group of subjects did not differ from the normalmirror function where inverted objects had been mentally rotated to the upright. For both functions, response time (RT) increased linearly from 0° to 180° and the slopes did not differ. The naming function for a second group of subjects did not differ from the normal-mirror function where inverted objects had been mentally flipped to the upright. For both functions, RT increased linearly at a similar rate from 0° to 120°, but decreased from 120° to 180°. The results are discussed in terms of theories of orientation-specific identification.     

Connectives and narrative text: The role of continuity

Connectives are text devices that signal the relation between adjacent sentences. Recently there has been a surge of research interest in the role played by connectives in on-line processing. The present research tested the hypothesis that connectives will impact on-line processing to the extent that they signal a text event that represents a departure from the continuity of the events stated in the text. In Experiment 1, participants generated sentences to follow a stimulus sentence. An additive, causal, or adversative connective (or no connective) was provided to serve as the first word of the participants’ sentence. Results showed that sentences generated in response to additive or causal connectives depicted text events that were continuous with the stimulus text. In contrast, sentences generated in response to adversative connectives depicted discontinuous text events. In Experiments 2 and 3, participants read coherent sentence pairs containing inappropriately placed additive, causal, or adversative connectives. Support for the continuity hypothesis was found when it was shown that adversative connectives led to the greatest amount of processing disruption, as measured by longer reading time on the postconnective sentence (Experiment 2) and lower ratings of coherence (Experiment 3). Future research in this area is discussed.