The effect of compressed speech on the ability of right-hemisphere-damaged patients to use context.

The ability of RHD patients to use context under conditions of increased processing demands was examined. Subjects monitored for words in auditorily presented sentences of three context types-normal, semantically anomalous, and random, at three rates of speech normal, 70% compressed (Experiment 1) and 60% compressed (Experiment 2). Effects of semantics and syntax were found for the RHD and normal groups under the normal rate of speech condition. Using compressed rates of speech, the effect of syntax disappeared, but the effect of semantics remained. Importantly, and contrary to expectations, the RHD group was similar to normals in continuing to demonstrate an effect of semantic context under conditions of increased processing demands. Results are discussed relative to contemporary theories of laterality, based on studies with normals, that suggest that the involvement of the left versus right hemisphere in context use may depend upon the type of contextual information being processed.

Context use by right-hemisphere-damaged individuals under a compressed speech condition.

The effect of increased processing demands on context use by RHD individuals was examined using a word-monitoring task. Subjects were required to monitor for a target word in sentences that were either normal, semantically anomalous, or both syntactically and semantically anomalous. Stimuli were presented at two rates of speech--normal and compressed to 70% of normal. Contrary to expectations, the RHD group performed similar to normals in demonstrating an effect of context at both rates of speech. Results are discussed relative to recent studies of normal brain functioning that suggest that the involvement of the LH versus the RH in context use depends upon the type of contextual information being processed.

Automatic versus strategic effects of phonology and orthography on auditory lexical access in brain-damaged patients as a function of inter-stimulus interval.

The influence of both phonological and orthographic information on auditory lexical access was examined in left- and right-hemisphere-damaged individuals using a lexical decision paradigm. Subjects were presented with prime-target pairs that were either phonologically related (tooth-youth), orthographically related (touch-couch), both phonologically and orthographically related (blood-flood), or unrelated (bill-tent), at two inter-stimulus intervals (ISI)--100 ms and 750 ms--to tap more automatic versus more strategic processing. All groups demonstrated effects of orthography at both ISIs (facilitory at 100 ms ISI and inhibitory at 750 ms ISI), supporting the findings by Leonard and Baum (1997) that effects of orthography emerge independent of site of brain damage and suggesting that orthographic effects in auditory word recognition tend to be largely strategic. A facilitory effect of phonology was also found for all groups at both ISIs. The findings are discussed in relation to theories of lexical activation in brain-damaged individuals.

On-line evidence for context use by right-brain-damaged patients.

The ability of right-brain-damaged (RBD) patients to use on-line contextual information in a word-monitoring task was examined. Subjects were required to monitor for target words in the contexts of both normal and semantically anomalous sentences. Similar to previous studies with normals (e.g., Marslen;Wilson & Tyler, 1980), the semantic integrity of the context was influential in the word-recognition process. Importantly, the RDB patients performed similarly to normals in showing context effects. These results were interpreted as substantiating the findings of Leonard, Waters, and Caplan (1997a, 1997b) that RBD patients do not present with a specific deficit in the use of contextual information. The results are discussed in terms of proposals that suggest that an impaired ability to use contextual information by RBD patients may be a function of increased processing demands.

The use of contextual information related to general world knowledge by right brain-damaged individuals in pronoun resolution.

This study investigated the ability of right brain-damaged individuals (RBD) to use contextual information to resolve ambiguous pronouns. Subjects were presented with sentence pairs and required to resolve the ambiguous pronoun in the second sentence. Contrary to the prevailing view that RBD patients have difficulty using contextual information to integrate language, the RBD group demonstrated a normal pattern of response, demonstrating a sensitivity to the pragmatic information contained in the leading sentence. They responded more quickly to sentences with a pragmatically constrained preferred referent than to those sentences for which there was no preferred referent. As well, they chose the preferred referent significantly more often than the non-preferred referent. These results suggest that RBD patients can use contextual information at the level of a minimal discourse (i.e., two sentences).

The use of contextual information by right brain-damaged individuals in the resolution of ambiguous pronouns.

Two experiments were conducted with the primary purpose of investigating the ability of right brain-damaged (RBD) individuals to use contextual information--at the level of the single sentence, in terms of the integration of information between clauses, and at the level of a minimal discourse (i.e., two sentences)--in the resolution of ambiguous pronouns. The investigation was extended to a group of left brain-damaged (LBD) and non-brain-damaged (NBD) individuals. Contrary to the prevailing view that RBD patients have difficulty in the use of contextual information to process language, both experiments were consistent in demonstrating that the RBD group was influenced by contextual information in a manner similar to that demonstrated by both the LBD and NBD groups.

The ability of right- and left-hemisphere-damaged individuals to produce and interpret prosodic cues marking phrasal boundaries.

Two experiments were conducted with the purpose of investigating the ability of right- and left-hemisphere-damaged individuals to produce and perceive the acoustic correlates to phrase boundaries. In the production experiment, the utterance pink and black and green was elicited in three different conditions corresponding to different arrangements of colored squares. Acoustic analyses revealed that both left- and right-hemisphere-damaged patients exhibited fewer of the expected acoustic patterns in their productions than did normal control subjects. The reduction in acoustic cues to phrase boundaries in the utterances of both patient groups was perceptually salient to three trained listeners. The perception experiment demonstrated a significant impairment in the ability of both left-hemisphere-damaged and right-hemisphere-damaged individuals to perceive phrasal groupings. Results are discussed in relation to current hypotheses concerning the cerebral lateralization of speech prosody.

The problem of generalizing to a language population: a "random" controversy.

The rationale behind the use of item statistics as well as objections to their use are reviewed. It is argued that investigators conducting language research with disordered populations should follow the example of those conducting language research with normal populations and consider calculating item statistics if they wish their results to generalize beyond the specific items tested.