Neural correlates of mapping from phonology to orthography in children performing an auditory spelling task

Age-related differences (9- to 15-year-olds) in the neural correlates of mapping from phonology to orthography were examined with functional magnetic resonance imaging (fMRI). Participants were asked to determine if two spoken words had the same spelling for the rime (corresponding letters after the first consonant or consonant cluster). Some of the word pairs had conflicting orthography and phonology (e.g. jazz-has, pint-mint) whereas other pairs had non-conflicting information (e.g. press-list, gate-hate) (see Table 1). There were age-related increases in activation for lexical processing (across conflicting and non-conflicting conditions) in left inferior parietal lobule, suggesting that older children have a more elaborated system for mapping between phonology and orthography that includes connections at different grain sizes (e.g. phonemes, onset-rimes, syllables). In addition, we found that the conflicting conditions had lower accuracy, slower reaction time and greater activation in left inferior frontal gyrus as compared to non-conflicting conditions. Higher accuracy was also correlated with greater activation in left inferior frontal gyrus for the most difficult conflicting condition (e.g. jazz-has). The finding of both a conflict effect and a correlation with accuracy in left inferior frontal gyrus suggests that this region may be involved in resolving the conflict between orthographic and phonological representations.     

Sensory noise explains auditory frequency discrimination learning induced by training with identical stimuli

Thresholds in various visual and auditory perception tasks have been found to improve markedly with practice at intermediate levels of task difficulty. Recently, however, there have been reports that training with identical stimuli, which, by definition, were impossible to discriminate correctly beyond chance, could induce as much discrimination learning as could training with different stimuli. These surprising findings have been interpreted as evidence that discrimination learning can occur in the absence of perceived differences between stimuli and need not involve the fine-tuning of a discrimination mechanism. Here, we show that these counterintuitive findings of discrimination learning without discrimination can be understood simply by considering the effect of internal noise on sensory representations. Because of such noise, physically identical stimuli are unlikely to be perceived as being strictly identical. We show that, given empirically derived levels of sensory noise, perceived differences evoked by identical stimuli are actually not much smaller than those induced by the physical differences typically used in discrimination-learning experiments. We suggest that findings of discrimination learning with identical stimuli can be explained without implicating any fundamentally new learning mechanism.     

Stress reduces attention to irrelevant information: Evidence from the Stroop task

Stroop interference can be reduced by stress, and this has been taken as evidence that stress decreases the attention paid to irrelevant information, a theory known as ‘Easterbrook’s hypothesis’. This contradicts more recent theories, which state that attentional control deteriorates in stress. Fifty-five participants undertook a Stroop task under high stress (loud white noise) and low stress conditions. Attention to the irrelevant word information was assessed by manipulating the proportion of congruent trials (e.g. the word RED in the colour red); it is known that Stroop interference increases when many such trials are presented. This effect was reduced when participants were stressed, which is evidence that stress does indeed reduce attention to irrelevant information. This pattern of results was not present in participants with low working memory spans, presumably because these participants had less attentional control. These findings highlight an important weakness in contemporary theories of cognition in stress.     

The development of specialized brain systems in reading and oral-language.

Functional magnetic resonance imaging (fMRI) was used to examine differences between children (9-12 years) and adults (21-31 years) in the distribution of brain activation during word processing. Orthographic, phonologic, semantic and syntactic tasks were used in both the auditory and visual modalities. Our two principal results were consistent with the hypothesis that development is characterized by increasing specialization. Our first analysis compared activation in children versus adults separately for each modality. Adults showed more activation than children in the unimodal visual areas of middle temporal gyrus and fusiform gyrus for processing written word forms and in the unimodal auditory areas of superior temporal gyrus for processing spoken word forms. Children showed more activation than adults for written word forms in posterior heteromodal regions (Wernicke's area), presumably for the integration of orthographic and phonologic word forms. Our second analysis compared activation in the visual versus auditory modality separately for children and adults. Children showed primarily overlap of activation in brain regions for the visual and auditory tasks. Adults showed selective activation in the unimodal auditory areas of superior temporal gyrus when processing spoken word forms and selective activation in the unimodal visual areas of middle temporal gyrus and fusiform gyrus when processing written word forms.     

Antialiasing: A technique for smoothing jagged lines on a computer graphics image—an implementation on the Amiga

Images displayed on computer graphics displays often suffer from the presence of aliasing artifacts that give a jagged appearance to lines or polygon edges displayed on the screen. This paper details the problems associated with these artifacts and presents a method for drawingantialiased lines—ones in which the artifacts have been considerably reduced. The line-drawing routine is further developed to incorporategamma correction, to take into account the nonlinear relationship between the intensity of the light emission from the phosphor of the monitor and the grayscale values used to control the intensity on the screen.     

Preferences for Dispute Resolution Procedures as a Function of Intentionality,Consequences, Expected Future Interaction,and Power1

Two studies investigated preferences for dispute resolution procedures as a function of several situational factors. Study 1 varied intentionality of the conflict, consequences, and expected future interaction between the disputants. The data indicated that 3rd-party procedures were most preferred when the wrongdoing was intentional and when there were high consequences. Study 2 varied intentionality, consequences and the power relationship between the 2 disputants. The relevant effects of Study 1 were replicated, and it was found that arbitration and advisory arbitration were most preferred when the conflict involved parties of equal power. The study supports the general view that research in several domains can be integrated into a coherent pattern of effects relevant for dispute resolution.     

Acquisition of the Mental State Verb Know by 2- to 5-Year-Old Children

The production of the cognitive internal state word know by four 2- to 5-year-old children and their parents was examined. The levels of meaning of cognitive words can be categorized hierarchically along the dimensions of conceptual difficulty and abstractness (see Booth & Hall, 1995). The present study found that children and their parents expressed low levels of meaning less frequently, whereas they expressed high levels of meaning more frequently as a function of age. The children's use of know was also correlated positively with (1) their number of different words produced suggesting that cognitive words are related to more general semantic processes, and (2) with parental use of those same cognitive words suggesting that parental linguistic input may be an important mechanism in cognitive word acquisition. Finally, young children tended to use know more to refer to themselves than to refer to others, whereas their parents tended to use know equally to refer to self and others. The importance of cognitive words in a theory of language acquisition is discussed.