Acquired aphasia in children and the ontogenesis of hemispheric functional specialization.

We have described a series of 26 cases of cortical lesions in children from $\text{3}\text{1}\text{2}$ to 15 years of age (17 left-sided, six right-sided, three bilateral), in which 19 had varying degrees of language disturbance. We have attempted to establish the nature and evolution of these aphasic disorders, and have compared our observations to those previously published. Our analysis appears to indicate a relative hemispheric equipotentiality which permits the transfer of language representation to the opposite hemisphere in the case of a unilateral lesions in childhood. This conclusion, however, has at least the appearance of being in conflict with other reported findings, viz., those deriving from psychometric testing of subjects with unilateral perinatal lesions; and those concerning studies of fetal and newborn brains which suggest a very early, if not innate, hemispheric specialization.The fact of this discrepancy has lead us to reconsider the concept of a critical period as defined by Lenneberg. In this respect, we have also discussed the possibility of a partial transfer of language representation, of an intrahemispheric reorganization by intact “uncommitted” areas (P. Goldman), and finally, the need for an adequate stimulus during a given period in order for a preformed area to become functional.     

Spoonish spanerisms: A lexical bias effect in Spanish

Lexical bias is the tendency for phonological errors to form existing words at a rate above chance. This effect has been observed in experiments and corpus analyses in Germanic languages, but S. del Viso, J. M. Igoa, and J. E. García-Albea (1991) found no effect in a Spanish corpus study. Because lexical bias plays an important role in the debate on interactivity in language production, the authors reconsidered its absence in Spanish. A corpus analysis, which considered relatively many errors and which used a method of estimating chance rate that is relatively independent of total error number, and a speech-error elicitation experiment provided converging evidence for lexical bias in Spanish. The authors conclude that the processing mechanisms underlying this effect hold cross-linguistically.     

Remembering the orientation of newly learned characters depends on the associated writing knowledge: a comparison between handwriting and typing

Recent data support the idea that movements play a crucial role in letter representation and suggest that handwriting knowledge contributes to visual recognition of letters. If so, using different motor activities while subjects are learning to write should affect their subsequent recognition performances. In order to test this hypothesis, we trained adult participants to write new characters either by copying them or by typing them on a keyboard. After three weeks of training we ran a series of tests requiring visual processing of the characters' orientation. Tests were ran immediately, one week after, and three weeks after the end of the training period. Results showed that when the characters had been learned by typing, they were more frequently confused with their mirror images than when they had been written by hand. This handwriting advantage did not appear immediately, but mostly three weeks after the end of the training. Our results therefore suggest that the stability of the characters' representation in memory depends on the nature of the motor activity produced during learning.     

Determinants of lexical access in speech production: Role of word frequency and age of acquisition

The main determinants of lexical access in speech are considered to be a word's age of acquisition (AoA) and its frequency of occurrence in a speaker's experience. It is unclear whether and how these variables interact, although they are commonly observed to be correlated, for the few studies that address the issue have reported inconsistent findings. An influential view of AoA in lexical processing (Ellis and Lambon Ralph, 2000) predicts stronger frequency effects for items acquired later in life than for those acquired at an early age. Five experiments were designed to investigate the possible interaction of AoA and frequency effects in speech. We found that the interaction between word frequency and AoA was not robust and that, contrary to expectation, the effect of word frequency was greater for words acquired earlier in life than for those acquired later. The implications of our findings are discussed.     

Does a regional accent perturb speech processing?

The processing costs involved in regional accent normalization were evaluated by measuring differences in lexical decision latencies for targets placed at the end of sentences with different French regional accents. Over a series of 6 experiments, the authors examined the time course of comprehension disruption by manipulating the duration and presentation conditions of accented speech. Taken together, the findings of these experiments indicate that regional accent normalization involves a short-term adjustment mechanism that develops as a certain amount of accented signal is available, resulting in a temporary perturbation in speech processing.     

Task-order coordination in dual-task performance and the lateral prefrontal cortex: an event-related fMRI study

A crucial demand in dual tasks suffering from a capacity limited processing mechanism is task-order scheduling, i.e. the control of the order in which the two component tasks are processed by this limited processing mechanism. The present study aims to test whether the lateral prefrontal cortex (LPFC) is associated with this demand. For this, 15 participants performed a psychological refractory paradigm (PRP) type dual task in an event-related functional magnetic resonance (fMRI) experiment. In detail, two choice reaction tasks, a visual (response with right hand) and an auditory (response with left hand), were presented with a temporal offset of 200 ms, while the participants were required to respond to the tasks in the order of their presentation. Importantly, the presentation order of the tasks changed randomly. Based on previous evidence, we argue that trials in which the present task order changed as compared to the previous trial (different-order trials) impose higher demands on task coordination than same-order trials do. The analyses showed that cortical areas along the posterior part of the left inferior frontal sulcus as well as the right posterior middle frontal gyrus were more strongly activated in different-order than in same-order trials, thus supporting the conclusion that one function of the LPFC for dual-task performance is the temporal coordination of two tasks. Furthermore, it is discussed that the present findings favour the active scheduling over the passive queuing hypothesis of dual-task processing.     

The “prawn-in-the-tube” procedure in the cuttlefish: Habituation or passive avoidance learning?

This study examines whether or not habituation contributes to the regulation of the inhibition of predatory behavior observed during the "prawn-in-the-tube" training procedure. When presented with prawns that are visible behind glass but untouchable, cuttlefish promptly learn to inhibit their capture attempts. The first three experiments demonstrated that the acquired response in the course of training cannot be dishabituated. The fourth experiment demonstrated that the repeated application of a brief visual prawn stimulus, one that is terminated before the cuttlefish can strike, decreases attack latencies. Taken together, the results of this study establish that habituation does not play a significant role in this learning task. In fact, the present findings strengthen the results of previous studies suggesting that passive avoidance learning contributes to the regulation of the inhibition of predatory behavior.