A population-based twin study of parentally reported tactile and auditory defensiveness in young children.

Some adults and children exhibit defensive behaviors to tactile or auditory stimulation. These symptoms occur not only in subsets of children with ADHD, autism, and Fragile X syndrome, but also in the apparent absence of accompanying disorders. Relatively little research explores the correlates and antecedents of sensory defensiveness. Using a population-based sample of 1,394 toddler-aged twins, mothers reported on tactile and auditory defensiveness, temperament, and behavior problems. The incidence of defensive symptoms was widely distributed, with some accumulation of cases in the extreme range. Girls were overrepresented in the extreme tactile defensiveness group. Both auditory and tactile defensiveness were modestly associated with fearful temperament and anxiety, but they were relatively distinct from other common dimensions of childhood behavioral dysfunction. Twin correlations for the full range of scores and concordance rates for the extremes suggested moderate genetic influences, with some indication that the tactile domain might be more heritable than the auditory domain.

Language deficits, localization, and grammar: evidence for a distributive model of language breakdown in aphasic patients and neurologically intact individuals.

Selective deficits in aphasic patients' grammatical production and comprehension are often cited as evidence that syntactic processing is modular and localizable in discrete areas of the brain (e.g., Y. Grodzinsky, 2000). The authors review a large body of experimental evidence suggesting that morpho-syntactic deficits can be observed in a number of aphasic and neurologically intact populations. They present new data showing that receptive agrammatism is found not only over a range of aphasic groups, but is also observed in neurologically intact individuals processing under stressful conditions. The authors suggest that these data are most compatible with a domain-general account of language, one that emphasizes the interaction of linguistic distributions with the properties of an associative processor working under normal or suboptimal conditions.

Right and left hemisphere cooperation for drawing predictive and coherence inferences during normal story comprehension.

In three experiments, healthy young participants listened to stories promoting inferences and named inference-related test words presented to the right visual field-Left Hemisphere (rvf-LH) or to the left visual field-Right Hemisphere (lvf-RH). Participants showed priming for predictive inferences only for target words presented to the lvf-RH; in contrast, they showed priming for coherence inferences only for target words presented to the rvf-LH. These results, plus the fact that patients with RH brain damage have difficulty drawing coherence inferences and do not show inference-related priming, suggest that information capable of supporting predictive inferences is more likely to be initially activated in the RH than the LH, but following coherence breaks these concepts (now coherence inferences) are completed in the LH. These results are consistent with the theory that the RH engages in relatively coarse semantic coding, which aids full comprehension of discourse.

Functional neuroanatomy of the cognitive process of mapping during discourse comprehension.

We used functional magnetic resonance imaging (fMRI) to identify brain regions involved in the process of mapping coherent discourse onto a developing mental representation. We manipulated discourse coherence by presenting sentences with definite articles (which lead to more coherent discourse) or indefinite articles (which lead to less coherent discourse). Comprehending connected discourse, compared with reading unrelated sentences, produced more neural activity in the right than left hemisphere of the frontal lobe. Thus, the right hemisphere of the frontal lobe is involved in some of the processes underlying mapping. In contrast, left-hemisphere structures were associated with lower-level processes in reading (such as word recognition and syntactic processing). Our results demonstrate the utility of using fMRI to investigate the neural substrates of higher-level cognitive processes such as discourse comprehension.

Inhibitory control during sentence comprehension in individuals with dementia of the Alzheimer type.

In two experiments we investigated the extent to which individuals with dementia of the Alzheimer type (DAT) manage the activation of contextually appropriate and inappropriate meanings of ambiguous words during sentence comprehension. DAT individuals and healthy older individuals read sentences that ended in ambiguous words and then determined if a test word fit the overall meaning of the sentence. Analysis of response latencies indicated that DAT individuals were less efficient than healthy older individuals at suppressing inappropriate meanings of ambiguous words not implied by sentence context, but enhanced appropriate meanings to the same extent, if not more, than healthy older adults. DAT individuals were also more likely to allow inappropriate information to actually drive responses (i.e., increased intrusion errors). Overall, the results are consistent with a growing number of studies demonstrating impairments in inhibitory control, with relative preservation of facilitatory processes, in DAT.

Cerebral mechanisms for suppression of inappropriate information during sentence comprehension.

In two experiments we investigated the extent to which interference from contextually inappropriate information was attenuated or suppressed over time in the two cerebral hemispheres during sentence comprehension. Subjects viewed centrally presented sentences ending in either a homophone or a homograph and made speeded judgments as to whether a laterally presented test word was related to the overall meaning of the sentence. Suppression of contextually inappropriate forms of homophones was found when test words were presented to either hemifield, but suppression of inappropriate senses of homographs was found only when test words were presented to the right visual hemifield. The results from the homograph experiment are consistent with the hypothesis that right and left hemisphere semantic selection systems operate in qualitatively different ways. The results from the homophone experiment suggest that while the left hemisphere may be more efficient at suppression, both hemispheres possess the ability to suppress inappropriate information to some degree.

Cataphoric devices in spoken discourse.

We propose that speakers mark key words with cataphoric devices. Cataphoric devices are counterparts to anaphoric devices: Just as anaphoric devices enable backward reference, cataphoric devices enable forward reference. And just as anaphoric devices mark concepts that have been mentioned before, cataphoric devices mark concepts that are likely to be mentioned again. We investigated two cataphoric devices: spoken stress and the indefinite this. Our experiments demonstrated three ways that concepts marked by cataphoric devices gain a privileged status in listeners' mental representations: Cataphoric devices enhance the activation of the concepts that they mark; cataphoric devices suppress the activation of previously mentioned concepts; and cataphoric devices protect the concepts that they mark from being suppressed by subsequently mentioned concepts.

The advantage of first mention in Spanish.

An advantage of first mention-that is, faster access to participants mentioned first in a sentence-has previously been demonstrated only in English. We report three experiments demonstrating that the advantage of first mention occurs also in Spanish sentences, regardless of whether the first-mentioned participants are syntactic subjects, and regardless, too, of whether they are proper names or inanimate objects. Because greater word-order flexibility is allowed in Spanish than in English (e.g., nonpassive object-verb-subject constructions exist in Spanish), these findings provide additional evidence that the advantage of first mention is a general cognitive phenomenon.

The mechanism of suppression: a component of general comprehension skill.

We investigated whether the cognitive mechanism of suppression underlies differences in adult comprehension skill. Less skilled comprehenders reject less efficiently the inappropriate meanings of ambiguous words (e.g., the playing card vs. garden tool meaning of spade), the incorrect forms of homophones (e.g., patients vs. patience), the highly typical but absent members of scenes (e.g., a tractor in a farm scene), and words superimposed on pictures or pictures surrounding words. However, less skilled comprehenders are not less cognizant of what is contextually appropriate; in fact, they benefit from a biasing context just as much (and perhaps more) as more skilled comprehenders do. Thus, less skilled comprehenders do not have difficulty enhancing contextually appropriate information. Instead, we suggest that less skilled comprehenders suffer from a less efficient suppression mechanism, which we conclude is an important component of general comprehension skill.

Investigating differences in general comprehension skill.

For adults, skill at comprehending written language correlates highly with skill at comprehending spoken language. Does this general comprehension skill extend beyond language-based modalities? And if it does, what cognitive processes and mechanisms differentiate individuals who are more versus less proficient in general comprehension skill? In our first experiment, we found that skill in comprehending written and auditory stories correlates highly with skill in comprehending nonverbal, picture stories. This finding supports the hypothesis that general comprehension skill extends beyond language. We also found support for the hypotheses that poorer access to recently comprehended information marks less proficient general comprehension skill (Experiment 2) because less skilled comprehenders develop too many mental substructures during comprehension (Experiment 3), perhaps because they inefficiently suppress irrelevant information (Experiment 4). Thus, the cognitive processes and mechanisms involved in capturing and representing the structure of comprehensible information provide one source of individual differences in general comprehension skill.

The cataphoric use of the indefinite this in spoken narratives.

Are concepts that were introduced with the unstressed, indefinite article this, as opposed to the indefinite a/an, more accessible from listeners' mental representations? Subjects heard and then verbally continued each of a series of informal narratives. The last clause of each narrative introduced a new noun phrase that began with either the indefinite this or the indefinite a/an (e.g., this egg or an egg). When the concepts were introduced with the indefinite this, the subjects referred to them more frequently, often within the first clauses that they produced, and typically via pronouns. In contrast, when the concepts were introduced with a/an, the subjects referred to them less frequently and typically via full noun phrases. Thus, concepts introduced with the indefinite this were more accessible; therefore, the indefinite this appears to operate cataphorically to improve referential access.

Mechanisms that improve referential access.

Two mechanisms, suppression and enhancement, are proposed to improve referential access. Enhancement improves the accessibility of previously mentioned concepts by increasing or boosting their activation; suppression improves concepts' accessibility by decreasing or dampening the activation of other concepts. Presumably, these mechanisms are triggered by the informational content of anaphors. Six experiments investigated this proposal by manipulating whether an anaphoric reference was made with a very explicit, repeated name anaphor or a less explicit pronoun. Subjects read sentences that introduced two participants in their first clauses, for example, "Ann predicted that Pam would lose the track race," and the sentences referred to one of the two participants in their second clauses, "but Pam/she came in first very easily." While subjects read each sentence, the activation level of the two participants was measured by a probe verification task. The first two experiments demonstrated that explicit, repeated name anaphors immediately trigger the enhancement of their own antecedents and immediately trigger the suppression of other (nonantecedent) participants. The third experiment demonstrated that less explicit, pronoun anaphors also trigger the suppression of other nonantecedents, but they do so less quickly--even when, as in the fourth experiment, the semantic information to identify their antecedents occurs prior to the pronouns (e.g., "Ann predicted that Pam would lose the track race. But after winning the race, she..."). The fifth experiment demonstrated that more explicit pronouns--pronouns that match the gender of only one participant-trigger suppression more powerfully. A final experiment demonstrated that it is not only rementioned participants who improve their referential access by triggering the suppression of other participants; newly introduced participants do so too (e.g., "Ann predicted that Pam would lose the track race, but Kim..."). Thus, both suppression and enhancement improve referential access, and the contribution of these two mechanisms is a function of explicitness. The role of these two mechanisms in mediating other referential access phenomena is also discussed.

Remembering left-right orientation of pictures.

In a study of recognition memory for pictures, we observed an asymmetry in classifying test items as "same" versus "different" in left-right orientation: Identical copies of previously viewed items were classified more accurately than left-right reversals of those items. Response bias could not explain this asymmetry, and, moreover, correct "same" and "different" classifications were independently manipulable: Whereas repetition of input pictures (one vs. two presentations) affected primarily correct "same" classifications, retention interval (3 hr vs. 1 week) affected primarily correct "different" classifications. In addition, repetition but not retention interval affected judgments that previously seen pictures (both identical and reversed) were "old". These and additional findings supported a dual-process hypothesis that links "same" classifications to high familiarity, and "different" classifications to conscious sampling of images of previously viewed pictures.

Resolving 20 years of inconsistent interactions between lexical familiarity and orthography, concreteness, and polysemy.

Numerous word recognition studies conducted over the past 2 decades are examined. These studies manipulated lexical familiarity by presenting words of high versus low printed frequency and most reported an interaction between printed frequency and one of several second variables, namely, orthographic regularity, semantic concreteness, or polysemy. However, the direction of these interactions was inconsistent from study to study. Six new experiments clarify these discordant results. The first two demonstrate that words of the same low printed frequency are not always equally familiar to subjects. Instead, subjects' ratings of "experimental familiarity" suggest that many of the low-printed-frequency words used in prior studies varied along this dimension. Four lexical decision experiments reexamine the prior findings by orthogonally manipulating lexical familiarity, as assessed by experiential familiarity ratings, with bigram frequency, semantic concreteness, and number of meanings. The results suggest that of these variables, only experiential familiarity reliably affects word recognition latencies. This in turn suggests that previous inconsistent findings are due to confounding experiential familiarity with a second variable.