Learning to divide the labor: an account of deficits in light and heavy verb production

Theories of sentence production that involve a convergence of activation from conceptual‐semantic and syntactic‐sequential units inspired a connectionist model that was trained to produce simple sentences. The model used a learning algorithm that resulted in a sharing of responsibility (or “division of labor”) between syntactic and semantic inputs for lexical activation according to their predictive power. Semantically rich, or “heavy”, verbs in the model came to rely on semantic cues more than on syntactic cues, whereas semantically impoverished, or “light”, verbs relied more on syntactic cues. When the syntactic and semantic inputs were lesioned, the model exhibited patterns of production characteristic of agrammatic and anomic aphasic patients, respectively. Anomic models tended to lose the ability to retrieve heavy verbs, whereas agrammatic models were more impaired in retrieving light verbs. These results obtained in both sentence production and single‐word naming simulations. Moreover, simulated agrammatic lexical retrieval was more impaired overall in sentences than in single‐word tasks, in agreement with the literature. The results provide a demonstration of the division‐of‐labor principle, as well as general support for the claim that connectionist learning principles can contribute to the understanding of non‐transparent neuropsychological dissociations.     

Perception of intersensory synchrony: A tutorial review

For most multisensory events, observers perceive synchrony among the various senses (vision, audition, touch), despite the naturally occurring lags in arrival and processing times of the different information streams. A substantial amount of research has examined how the brain accomplishes this. In the present article, we review several key issues about intersensory timing, and we identify four mechanisms of how intersensory lags might be dealt with: by ignoring lags up to some point (a wide window of temporal integration), by compensating for predictable variability, by adjusting the point of perceived synchrony on the longer term, and by shifting one stream directly toward the other.     

Eyetracking for two-person tasks with manipulation of a virtual world

Eyetracking facilities are typically restricted to monitoring a single person viewing static images or prerecorded video. In the present article, we describe a system that makes it possible to study visual attention in coordination with other activity during joint action. The software links two eyetracking systems in parallel and provides an on-screen task. By locating eye movements against dynamic screen regions, it permits automatic tracking of moving on-screen objects. Using existing SR technology, the system can also cross-project each participant’s eyetrack and mouse location onto the other’s on-screen work space. Keeping a complete record of eyetrack and on-screen events in the same format as subsequent human coding, the system permits the analysis of multiple modalities. The software offers new approaches to spontaneous multimodal communication: joint action and joint attention. These capacities are demonstrated using an experimental paradigm for cooperative on-screen assembly of a two-dimensional model. The software is available under an open source license.     

Vertical perceptual span and the processing of visual signals in reading

A previous study by Pollatsek et al. ( 1993 ) claims that the perceptual span in reading is restricted to the fixated line, i.e. readers typically focus their visual attention on the line of text being read. The present study investigated whether readers make use of content structure signals (paragraph indentations and topic headings) present several lines away from the currently fixated line. We reasoned that as these signals are low-resolution visual objects (as opposed to letter and word identity), readers may attend to them even if they are located some distance away from the fixated line. Participants read a hierarchically organized multi-topic expository text containing structure signals in either a normal condition or a window condition, where the text disappeared above and below a vertical 3° gaze-contingent region. After reading, participants were asked to produce a written recall of the text. The results showed that the overall reading rate was not affected by the window. Nevertheless, the headings were reread more in the normal condition than in the window one. In addition, more topics were recalled in the normal than in the window condition. We interpret the results as indicating that the readers visually attend to useful text layout features while considering bigger units than single text lines. The perception of topic headings located away from the fixated line may favour long-range regressions towards them, which in turn may favour text comprehension. This claim is consistent with previous studies that showed that look-back fixations to headings are performed with an integrative intent.     

Disentangling cross-language orthographic neighborhood from markedness effects in L2 visual word recognition

Psychonomic Bulletin & Review - Previous research has reported that lexical access in bilinguals is language non-selective. In the present study, we explored the extent to which cross-language...