Talking nets: a multiagent connectionist approach to communication and trust between individuals

A multiagent connectionist model is proposed that consists of a collection of individual recurrent networks that communicate with each other and, as such, is a network of networks. The individual recurrent networks simulate the process of information uptake, integration, and memorization within individual agents, and the communication of beliefs and opinions between agents is propagated along connections between the individual networks. A crucial aspect in belief updating based on information from other agents is the trust in the information provided. In the model, trust is determined by the consistency with the receiving agents' existing beliefs and results in changes of the connections between individual networks, called trust weights. These weights lead to a selective propagation and thus to the filtering out of less reliable information, and they implement H. P. Grice's (1975) maxims of quality and quantity in communication. The unique contribution of communicative mechanisms beyond intrapersonal processing of individual networks was explored in simulations of key phenomena involving persuasive communication and polarization, lexical acquisition, spreading of stereotypes and rumors, and a lack of sharing unique information in group decisions.     

Delayed judgments of learning cause both a decrease in absolute accuracy (calibration) and an increase in relative accuracy (resolution)

A version of the PRAM methodology that permits an analytical evaluation of judgment of learning (JOL) accuracy was used for the first time to assess absolute accuracy (specifically, calibration). Results are reported from a new experiment in which Swahili-English translation equivalents were studied, followed sometime later (either immediately, approximately 1 min, or approximately 8 min) by pre-JOL recall and JOLs, and followed eventually by final recall. The calibration accuracy for predicting final recall decreased as the delay between study and JOL increased, with the decrease being most dramatic when only items that were recalled at the time of the JOL were considered. In contrast, relative accuracy (as measured by an overall gamma) improved as the delay between study and JOL increased. Participants appear insensitive to the combined effects of the recallability of the items at the time of the JOLs and of the delay between JOL and testing on the accuracy of JOLs.     

Planning and task management in older adults: Cooking breakfast

The article describes a simulated "cooking breakfast" task in which participants must remember to start and stop cooking five foods so that all the foods are "ready" at the same time. In between starting and stopping operations, the participants also carried out a "table-setting" task as a filler activity. The breakfast task yields various measures of multitasking and executive control. Groups of younger and older adults performed the task; half of the participants in each group were bilinguals and the other half were monolinguals. The results showed substantial age-related decrements in most measures of executive control. Additionally, older bilinguals showed some advantages in task management over their monolingual peers.     

Neural localization of semantic context effects in electromagnetic and hemodynamic studies

Measures of electrical brain activity (event-related potentials, ERPs) have been useful in understanding language processing for several decades. Extant data suggest that the amplitude of the N400 component of the ERP is a general index of the ease or difficulty of retrieving stored conceptual knowledge associated with a word, which is dependent on both the stored representation itself, and the retrieval cues provided by the preceding context. Recordings from patients with brain damage, intracranial recordings, and magnetoencephalographic data implicate a (probably large portion of) the left temporal lobe as the largest source of the N400 semantic context effect, with a substantial but lesser contribution from the right temporal lobe. Event-related functional magnetic resonance (fMRI) studies using semantic context manipulations are dominated by observations of greater hemodynamic activity for incongruent sentence completions or semantically unrelated words than congruent or related words, consistent with the direction of the ERP effect. The locations of the hemodynamic effects show some variability across studies, but one commonly identified region is the left superior temporal gyrus, which is compatible with the electrophysiological results. A second commonly identified region in the fMRI studies is the left inferior frontal gyrus, which does not appear to make a substantial contribution to the N400 effect.     

Does functional neuroimaging solve the questions of neurolinguistics?

Neurolinguistic research has been engaged in evaluating models of language using measures from brain structure and function, and/or in investigating brain structure and function with respect to language representation using proposed models of language. While the aphasiological strategy, which classifies aphasias based on performance modality and a few linguistic variables, has been the most stable, cognitive neurolinguistics has had less success in reliably associating more elaborately proposed levels and units of language models with brain structure. Functional imaging emerged at this stage of neurolinguistic research. In this review article, it is proposed that the often-inconsistent superfluity of outcomes arising from functional imaging studies of language awaits adjustment at both "ends" of the process: model and data. Assumptions that our current language models consistently and reliably represent implicit knowledge within human cerebral processing are in line for major revision; and the promise of functional brain imaging to reveal any such knowledge structures must incorporate stable correlates of the imaging signal as dependent variable.