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Language processing and production seem to involve many areas of the brain (Garrett, 1995). Using positron emission tomography (PET), Howard, et al (1992) were able to identify a number of physically separate brain structures that become active during various language processing tasks. They found that physically discrete areas are responsible for auditory and visual word recognition and that these areas are separate from those involved in either word comprehension or production. Similarly, measurements of N 400 sensory evoked brain potentials have found that different areas of the brain are active during processing of coherent and incoherent sentences (Kutas & Hilliard, 1980; Nixon, Tivis, Varner, & Rohrbaugh, in press), suggesting that language processing may be a more global activity than has been generally believed.
Fried, Ojemann and Few (1981) suggest that activity in Broca's area and Wernicke's area is simultaneous, communication between these areas is both bi-directional and interactive, and a parallel rather than serial processing strategy is used. Mesulan (1990) characterizes Wernicke's area not as a discrete memory store of individual words but as: "a nodal bottleneck for accessing a distributed grid connectivity that contains information about sound-word-meaning relationships. " Similarly, Broca's area is thought to be a parallel activation network which is primarily responsible for the translation of word representations produced in Wernicke's area into corresponding action potentials (Mesulan, 1990). Other language processing activities occur throughout the brain, including the right hemisphere (Ross & Mesulan, 1979; Weintraub, Mesulan, & Kramer, 1981). Studies involving individuals with various localized brain injuries support this notion. Sartori, Miozzo and Job (1993) report cases in which the ability to name and describe inanimate objects is intact while the production of animal names and descriptions is significantly impaired. A similar dissociation is seen in the ability to correctly comprehend and define words which cannot be accurately pronounced (Goodman & Carmazza, 1986), spelled or written (Hillis & Carmazza, 1991; Patterson, 1986).
For instance, Ellis, Miller and Sin (1983) describe individuals who are able to recognize and write the names of objects but cannot pronounce the names or read out loud the descriptions of those objects which they have just written. Conversely, Goodwin and Carmazza (1986) cite cases of individuals who are able to correctly pronounce and define words orally, but cannot write or type them. The localization and identification of underlying systems which support speech production also provides support for a distributed processing model. Mandarin-speaking Broca's aphasics have been found to be unable to correctly produce or interpret linguistic tonal nuances (Packard, 1986) while English-speaking aphasics are unable to produce and evaluate word and sentence timing (Day & Shapiro, 1982). Ross, Edmondson, Seibert and Chan (1992) report that patients with inferior frontoparietal damage are unable to recognize the emotional content of spoken language. Shedlack, et al. (1991) propose that the tendency for left hemispheric dominance may arise out of a need for complex inhibitory mechanisms to moderate and coordinate the brain's various processing units.
If language processing is in fact accomplished by the activation of discrete processing units in various parts of the brain, and the level of activation of these units is modulated by excitatory and inhibitory mechanisms, then a distributed processing architecture is strongly indicated. Dennett (1991), however, maintains that no particular brain system exists which acts as interpreter or integrator of the output from these various processing elements, but rather that it is their interaction which produces a unified output. Recent advances in the computer sciences offer support for a parallel processing model of cognition. A number of computer based neural network models have been constructed which exhibit behavioral characteristics similar to human cognitive functions. An example of this is seen in the work of Herrmann, Ruppin and Usher (1993). Their network, based on computer simulated neurons, successfully learned concepts associated with the separation of information into hierarchical semantic classes and acquired the ability to form and use episodic associations.
Other neural network programs have been successful at such characteristically intelligent behaviors as speech perception (McCllelland & Elman, 1986; Warren & Warren, 1970), letter and word recognition (Walker, Ryder, & Schweikert, 1980) and even syntactic and semantic processing (Rumelhart, 1977). Computer simulated neural networks can also can also be made to exhibit neuro pathological behavior patterns such as paranoia (Vinogradov, King, & Huberman, 1992) and schizophrenia (Hoffman & Dorscha, 1989). While none of these computer simulations even begin to approach the complexity of human cognitive processing, they may offer an insight into the kind of architecture required to accomplish mind. Tooby and Cosmides (1995) assert: "the brain is more than a physical system: It is both a computational system and an evolved biological system. " The key word in this assertion is system.
The authors suggest that the brain not a single-function whole, but an organism, an array of very specific processing units, each evolving in response to an equally specific ecologically relevant problem. And these processors do not follow any forward-looking blueprint in their ongoing developmental progress. Each processing system, at every point along its evolutionary trajectory, exists and is passed on to future generations only on the basis of its immediate survival advantage. Therefore, Tooby and Cosmides argue, the concept that the brain evolved as a holistic, general-purpose processing unit is biologically implausible.
Consciousness, the most cherished human mental capacity, has long been thought of as too complex a phenomena to be produced through neural activity alone (Penrose, 1994; Searle, 1992). Recent investigations in neuroscience, however, do not support this notion (Kinsbourne, 1995). When considered as an information processing system, consciousness arises through the integration and organization of the output from preconscious representational systems (Dennett & Kinsbourne, 1992). The adaptive function of such a process, Kinsbourne (1988) suggests, is context. The ability to compare the output of various sensory systems allows the individual a greater understanding of how these various representations are interrelated. Further, the ability to compare current representations with those based on previous experience and stored in memory allows the individual to transcend the "concrete present stimuli = immediate response" barrier.
Recent biological adaptations have generated improvements to this basic system allowing the individual to compare current representational information with previous representational memories and to combine them in new ways, creating awareness not only of what is happening now and what happened previously, but what might happen in the future. It is through these basic neurological activities that consciousness arises (Kinsbourne, 1995). Similar research has demonstrated that language begins not as a means of communication, but as a representational system (Bickerton, 1992). The same neurological architecture which allows animals to perceive the presence of predators, Bickerton suggests, provides them with the ability to communicate that presence to others.
The interrelation between consciousness and symbolic communication begins when animals learn to lie (Jolly, 1996). Survival advantage accrues to those animals able not only to perceive the presence of food and recognize that other animals are present who would prevent them from obtaining that food, but can also realize that if they produce a "false" alarm call, indicating the presence of danger, the animal them from obtaining food will be tricked into flight. The transition of language from a representational to a communication system begins, says Jolly, when a species learns to mis-represent. Alexander (1989) suggests that the rapid brain growth which eventually produced Homo Sapiens's most characteristic feature took place after the species achieved ecological dominance and that the selective pressure responsible for that growth was intra-species social competition. Given the inter-relation between social complexity and language skills (Lock & Symes, 1996), the same social pressures responsible for rapid brain growth may well have also selected for maximally efficient language processing systems.
Manager and Johnson (1977) suggest that verbal information is encoded, structured and stored in memory in specific ways as this tends to increase the efficiency of storage and retrieval. Typically, the information received through the presentation of words, ideas and sentences is integrated into narrative stories (Thorndyke, 1977). Depending on the nature and context of the verbal information which is to be integrated, narratives can be structured to emphasize spatial relationships (Bower & Morrow, 1990), emotional content (Rehab, Kaplan, Weylman, Brownell, & Gardner, 1992), or grammatical features (Thorndyke, 1977). Also, narrative production is an important language processing system in that it provides the context for human social discourse and interpersonal relations (Rehab, 1992). Through the use of narratives, humans have acquired the ability to build mental models of their physical and social environment and use these to consider, predict, plan and explain the events which occur within that environment (Bower & Morrow, 1990).
In Human Communication As Narration: Toward A Philosophy Of Reason, Values And Action (1987), Fisher states: "Far from being one code among many that a culture may utilize for endowing experience with meaning, narrative is a methode, a human universal on the basis if which trans-cultural messages about their shared reality can be transmitted. " In formulating his narrative paradigm, Fisher (1987) proposes that rational thought and logical decision making are based on the inherent qualities of a narrative story. The truth of a thing is based on its narrative probability (how likely a story it tells) and fidelity (how internally consistent that story is). So valuable have narratives become, that it would be difficult for the human species to exist without them. So fundamental is narrative production to human nature, Fisher (1977) suggests, the species might best be classified as "Homo Narrans", man the narrator. Whether or not mankind's definitive characteristic is narrative production, the importance of this activity is clearly evident given the strength of the output it produces. Readers often remember and recall their narrative constructions of textual materials rather than the text itself (Bransford & Franks, 1971; Johnson-Laird, 1983).
That is, individuals are more likely to recall the organizing themes and salient features of a story rather than its grammatical details. Input to this system can be further modified by learned expectations (Hoffman & Mcglashan, 1993). Fisher and Goodman (1978) demonstrate that knowledge about relative sizes and spatial relationships between objects affects interpretation and even perception of verbal information related to them. Examples of this are seen in top-down processing strategies such as letter and word recognition and the interpretation of anomalous sentences.
The accuracy of response and response selection time required to correctly identify incomplete or ambiguous stimuli are significantly improved through the use of context-relevant information (Fisher & Bloom, 1985; Rumelhart, 1977; Simpson, Peterson, Castle, & Burgess, 1989). These two processes, whereby incoming information is integrated into a Gestalt and moderated by context-relevant expectations, help to improve the overall efficiency of the language processing system, provided of course that both systems are functioning properly and communicating interactively. While many clinical populations experience linguistic deficits, schizophrenics exhibit a wide range of problems associated with the processing, production and interpretation of language. Hoffman and Mcglashan (1993) suggest that this may result from a reduction in the overall number if pathways connecting various neural processing systems within the brain. It is suggested that neuronal decoupling results from the overruling of synaptic connections during critical developmental periods (Huttenlocher, 1979; Rate, Bourgeois, Eckenhoff, Zecevic, & Goldman-Radio, 1986). This phenomena would prevent the individual processing units from interacting effectively and producing a coherent output (Hyde, Ziegler, & Weinberger, 1992).
While this does not account for the mediating effects of antipsychotic medications (Weinberger, 1987), it does provide a theoretical framework capable of explaining many of the phenomena associated with schizophrenia (Hoffman & Mcglashan, 1993). Of particular interest is the schizophrenic's inability to use top-down processing strategies (Neisser, 1976) or form Gestalts (John & Hemsley, 1992). While many studies indicate that schizophrenics are not able to employ higher level cognitive processing, John and Hemsley (1992) find that, given sufficient time, similar results could be obtained using data driven or "bottom up" processing strategies. This is consistent with the findings reported by Hallford (1994, 1993).
On a facial recognition task, Hallford finds that schizophrenics are not inferior to community controls in the number of correct responses, but require significantly longer to choose the correct response. Following up on this preliminary work, Nixon, Hallford and Tivis (1996) report that schizophrenics were not inferior to community controls on other standard neuropsychological tests, such as the Trail-Making test (Rennick, 1972). This would seem to indicate that while schizophrenics may preserve at least some kinds of cognitive skills, those involving integrative information processing are more likely to be affected. From this deficit pattern, the authors conclude that investigations which attempt to establish processing deficits in schizophrenics must consider not only the accuracy of the processing system in question but the speed at which this processing occurs as well. A second processing deficit common in schizophrenics is the tendency to exhibit poorer overall linguistic processing than community controls. Gold, Randolph, Carpenter, Goldberg and Weinberger (1992) find that schizophrenics demonstrate impairment in the learning, recall, recognition and semantic encoding of verbal information.
Also, schizophrenics are found to form poorer social schemata (Corrigan, Wallace, & Green, 1992). These two deficit patterns, when considered together, suggest that schizophrenics would exhibit poorer narrative formation skills. Such an explanation would, Following Fisher's narrative paradigm (1987), tell a very likely and internally consistent story. The quality of narrative formation would be further compromised by the fact that schizophrenics tend to form associations based on irrelevant (Hemsley, 1987; Oades, Blank, & Eggers, 1992) and delusional (Vinogradov, King, & Huberman, 1992) information. While studies have been conducted which consider the various components of narrative construction in schizophrenics, none have addressed both the accuracy and speed of this linguistic processing system. Might schizophrenics be able to achieve linguistic parity, exercise equal social conceptualization and create narrative stories, if given sufficient time to do so?
The purpose of this investigation is to begin the task of considering this important issue. The current research project is based on the protocol designed and employed by Bransford and Franks (1971). Their work focuses on the tendency of verbal information contained in individual narrative sentences to become integrated into a more complex linguistic structure, called an idea set. They propose that once an idea set is formed, individuals will be unable to recall the exact structure and content of the individual sentences from which it is formed.
To test this theory, Bransford and Franks constructed four narrative stories, each containing four basic story elements. Each story was expressed in the form of a single idea set sentence containing all four story elements. From these idea set sentences were constructed test sentences containing either one, two or three story elements. The test sentences were then divided into two sets.
The first set OLD, consisting of one, two and three element sentences from each of the four idea sets, was used to present these idea sets to the participants. The second set NEW, containing the remaining test sentences, were not presented. Participants were read one of these test sentences and then given a ten second distracted (color naming) task. At the conclusion of the distracted task, participants were asked a question about the test sentence. This procedure was followed until all test sentences in the OLD set were presented. Sentences from the same idea set were not presented consecutively to ensure that idea set formation was not simply an artifact of serial presentation.
After a five minute delay, participants were shown all the test sentences (OLD and NEW) and the idea set sentence and asked to identify which of those sentences had been previously presented. In their study, Bransford and Franks asked the following empirical questions: 1. Would participants be able to distinguish between sentences that had been presented OLD and NEW sentences that were structurally similar and contained elements from the same idea set? 2. Would participants be more likely to report having previously seen sentences containing more story elements from the idea set, than those sentences containing fewer elements? The authors report that the four element Idea Set sentences are most often identified as having been previously seen even though these sentences were never actually presented. Also, three element sentences, whether previously presented or not, are more often recognized than sentences containing only one or two sentence elements.
This study suggests that information from contextually related sentences, even when those sentences are not presented consecutively, are stored and processed holistically. The current project attempts to apply a similar research protocol to schizophrenics and community controls. Some changes were made, however, to address the question of how information processing takes place in schizophrenics. Although schizophrenics have been shown to be inferior to controls in holistic and Gestalt formation (John & Hemsley, 1992; Knight, 1984), they are able to achieve similar results using bottom-up processing strategies if given enough time (Hemsley, 1987).
Therefore, a measure of response selection time was obtained in addition to the number of Idea Set and three element NEW sentences selected. In the recognition phase of this task, when subjects are asked to indicate whether or not they have seen the sentence presented, the time required for making their response will be collected. Also, as schizophrenics are more likely to incorporate irrelevant or incongruous information (Hemsley, 1987; Oades, Blank, & Eggers, 1992; Vinogradov, King, & Huberman, 1992), the current protocol includes two idea set sentences constructed so that when their four story elements are integrated into a unified whole, an ambiguous construct will be produced. In this study, the following hypotheses were addressed: 1. It is expected that schizophrenics will be inferior to controls with respect to holistic processing. Specifically, on the Narrative Recognition Task, schizophrenics will be less likely to indicate that the four element Idea Set sentence or the three element sentences had been seen previously.
Groups will not differ on the number of identified one and two element sentences. 2. Because of poorer top-down processing skills, it is expected that should schizophrenics report seeing the Idea Set sentence and sentences incorporating three story elements, the response selection time required to make these identifications will be longer than those of community controls. Groups will not differ, however, on the time to respond to one and two element sentences, which do not derive from the integration of information. 3. It is expected that community controls will be less likely to form idea sets based on incongruent sentence elements than schizophrenics. Schizophrenics will not differ in the number of congruent and incongruent constructs formed, nor on the time required for them to do so. Specifically, schizophrenics will be just as likely to indicate seeing incongruent Idea Set sentences as congruent ones.
Also, while controls will tend to respond more quickly when identifying congruent Idea Set sentences, schizophrenics will not perform differentially with respect to response selection time. Participants included 15 schizophrenics (10 males, 5 females) and 15 community controls (9 males, 6 females). Schizophrenics were recruited from both state funded and private inpatient facilities. Based on clinical chart review, all clinical patients were found to meet DSM-IV (American Psychiatric Association, Diagnostic and Statistical Manual of Mental Disorders, 1994) criteria for schizophrenia. Only those with a stable diagnosis, having been diagnosed, medicated and treated as a schizophrenic for at least five years, were asked to participate. Individuals receiving below normal IQ or mini-mental scores, or other chart-based indications of mental impairment were not included in this study.
Additionally, only those patients between the ages of 21 and 55, who had been in an inpatient facility long enough to be stabilized, that is, no longer experiencing hallucinations or exhibiting floridly psychotic behavior, but with less than 45 days of inpatient care were asked to participate. Information concerning the patient's current state was obtained directly from a psychiatric treatment professional responsible for that patient. These criteria were used to insure that any deficits identified in the clinical group resulted from the relatively stable symptom ology associated with schizophrenia and not from the effects of the normal process of aging, short term acute psychosis, or social deprivation resulting from long-term hospitalization. Community controls were recruited from the Oklahoma City catchment area using newspaper ads, fliers, and word-of mouth.
Every effort was made to insure that community controls did not differ significantly in age or years of completed education from the clinical group as these factors would be expected to correlate with most neuropsychological measures. Because of the rather limited subject pool, subjects were not directly matched with respect to gender and ethnic membership. The gender and racial distribution of each group is presented in Table 1 below. Gender and Ethnic Distribution By Group. Participants were excluded on the basis of medical, physical, neurological, or psychiatric problems as these might affect performance. Individuals indicating learning disabilities or poor academic performance were also excluded.
Also, community controls were excluded if currently taking any medications that might interact with cognitive function. Schizophrenics were not excluded because of current medication. All participants provided informed, written consent. All were assured that the information they provided would be numerically coded to insure confidentiality, and would not be published, released or used in any way that might harm, embarrass or affect the individual providing that information. Inpatient participants were assured that the information they provided was for research purposes only, that it would not be made available to anyone, including the clinical facility in which they resided, and that participation would not affect their treatment in any way. It was made clear that should a participant become upset, uncomfortable or otherwise concerned, he or she might withdraw from the study at any time.
Further, if the participant had any questions or concerns as a result of the experimental protocol, appropriate responses would be provided by the test administrator. The Cognitive Studies Laboratory Group Screen Packet (Oklahoma Center for Alcohol and Drug Related Studies, 1992) was used to obtain basic demographic information and measures likely to be correlated with cognitive function and determine appropriateness of potential participants for further testing. This packet is included in Appendix 1. Specific questions were asked which relate to the following areas of concern: Basic Demographics. The age, race, gender and number of years of completed education of each prospective participant was obtained. These measures were important as they were to be controlled between groups.
Substance Abuse. Objective measures of alcohol and substance use and abuse were gathered. These were used to evaluate appropriateness for continued participation. Individuals expressing a significant problem, or with heavy or frequent use were excused from further participation. Physiological and Psychiatric Status. Information concerning periods of unconsciousness, overdoses, suicide attempts, illnesses, injuries or other events which might affect the proper functioning of the central nervous system were obtained.
Neurologically impaired individuals and those indicating significant psychiatric problems, other than those relating to schizophrenia in the clinical group, were not tested. As overall verbal functioning and affective state might have a bearing on narrative construction, standardized tests were given to assess these issues and prevent possible confounds. Because the Shipley Vocabulary Test (Shipley, 1940) has been widely used with many clinical and control populations and is quickly and easily administered, it was used as a measure of overall verbal functioning. The Beck Depression Inventory (Beck, Steer, & Garden, 1988) and the Spielberger State Anxiety Inventory (Spielberger, 1983) were given so that an assessment of affective state at the time of testing can be obtained.
Narrative Acquisition Task. For this task, four narrative stories were constructed. Each of these narrative stories consisted of four simple relationships between concrete objects, which are to be integrated into a complete four element whole. These narrative stories are based on the idea sets and constructed by Bransford and Franks (1971). Two of the narrative stories used here are identical to the sentences used by Bransford and Franks (1971) and two were modified so that the four individual story elements, when integrated into a whole, would form an ambiguous idea set. The Narrative Recognition Task.
The recognition task consisted of a set of 28 sentences. These sentences included: 1) the four Idea Set sentences, each containing all four elements. These sentences were not presented in the acquisition task. 2) One of the two OLD sentences containing three, two and only one story element from each of the narrative stories presented in the acquisition task, and 3) an equivalent one, two, and three element NEW sentence from each narrative story that had not been presented in the narrative acquisition task. This experiment employs a pseudo-random design.
Individuals were assigned to groups based on the presence or absence of a clinical diagnosis of schizophrenia. The first fifteen volunteers meeting the selection criteria for either the community control or clinical group were tested. As the clinical participants were tested on the unit from which they were recruited, it was not possible for testing to take place without the experimenter being aware of the participant's group membership. To insure that the testing protocol and environment were as similar as possible for both groups, community controls were tested at the Cognitive Studies Laboratory facility.
Identical materials, instructions, and test administration procedures were employed for both groups. Dependent measures collected on this experimental protocol included accuracy and response selection time for responses to the sentences presented in the narrative recognition task. From each narrative story, twelve sentences were constructed. One sentence was constructed which contained all four story elements, three that contained three story elements, four that contained only two story elements, and four that contained only one story element. A complete listing of the four narrative stories and the sentences which comprise them can be found Appendix 2.
From these sentences were constructed the sets of sentences used in the acquisition and recognition portions of the task. Narrative Acquisition Task. For the acquisition task, six sentences were randomly selected from each narrative story; two three element sentences, two two element sentences, and two single element sentences. These 24 sentences were divided into four sets.
The construction criterion for these sets was as follows: 1) Sentences from the same narrative story can not be presented consecutively. 2) No more than two sentences from the same narrative story can occur in any set. 3) Only one three element sentence from the same story can occur in any set. 4) All sets must begin and end with sentences from different narrative stories. Given these constraints and the limited number of unique sentences generated in the four narratives, only one presentation order was possible. These sentences and their sequential ordering is presented in Appendix 2. Narrative Recognition Task. The recognition task was constructed using a combination of sentences presented in the narrative acquisition task OLD, similar sentences which were not presented in the acquisition task NEW, and of the Idea Set sentences.
This task consisted of 28 sentences in all. These sentences included: 1) the four Idea Set sentences containing all four elements of each story that were not presented in the acquisition task; 2) one of the two OLD sentences containing three, two and only one story element from each story which was presented in the acquisition task, and 3) an equivalent three, two and single element NEW sentence from each narrative story that was not used in the acquisition task. These sentences are presented in Appendix 2. Dependent Measures.
As indicated earlier, it was expected that community controls would be more likely to believe that they have previously seen the Idea Set sentence, and NEW sentences containing three story elements, than OLD sentences containing only one or two story elements. Schizophrenics, exhibiting decreased Gestalt formation ability, would therefore be less likely to indicate seeing the Idea Set sentence and NEW sentences which were not presented in the acquisition task than controls. Therefore, schizophrenics were expected to be more accurate at correctly recognizing OLD sentences and rejecting both the Idea Set sentence and NEW sentences. In order to test this hypothesis, three measures were needed: 1) the number of correct OLD sentences identified, 2) the number of Idea Set sentences correctly rejected, and 3) the number of NEW sentences correctly rejected. It has also been suggested that community controls would be less likely to form Idea Sets when the individual story elements form an ambiguous whole.
Schizophrenics, however, are expected to be no less likely to form Idea Sets containing incongruent story elements than congruent ones. In order to test this hypothesis two measures are needed: 1) the number of congruent Idea Set sentences correctly rejected, and 2) the number of incongruent Idea Set sentences rejected. Lastly, it is suggested that schizophrenics may be able to compensate for poorer Gestalt formation if given sufficient time in which to employ bottom up processing strategies. Thus, it is predicted that paranoid schizophrenics will exhibit longer response selection times when indicating that the Idea Set sentence and NEW three element sentences, requiring information integration, were seen previously. Further, the time required to correctly identify OLD and reject NEW sent...
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