Easier tasks can have higher processing loads: Task difficulty and cognitive resource limitations in schizophrenia.

A differential deficit on the more difficult of 2 cognitive tasks has been found in numerous studies of schizophrenia. Resource limitations, rather than impairments in particular cognitive abilities, can explain these findings. Researchers often match tasks for difficulty level (healthy participant performance) to rule out resource limitations. This assumes processing resource load can be estimated from task difficulty, which is not always the case. A direct measure of resource allocation is needed. In this study, pupillary responses were recorded to index resource allocation (greater dilation indicates greater allocation) during performance of the digit span distractibility task in participants with schizophrenia (n = 35) and nonpsychiatric participants (n = 35). Nonpsychiatric participants recalled significantly more digits in the distraction, relative to the neutral, condition but also showed significantly greater pupil dilation in the distraction condition. The psychometrically "easier" condition, therefore, had a higher processing load. Participants with schizophrenia showed greater impairment relative to nonpsychiatric participants in the distraction condition. This finding cannot be attributed to a deficit in distractibility, however, because poorer performance was found in the higher-load condition, so resource limitations cannot be ruled out. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Task difficulty and conformity pressures.

This study using 60 Ss showed that conformity pressures are more easily exerted when the person is poorly informed with respect to questions of general information. When certain of the correct answers, the person is more easily able to resist pressures, but when uncertain he is more prone to use supplemental external information as the basis for making responses. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Context-processing deficits in schizophrenia: Converging evidence from three theoretically motivated cognitive tasks.

To test the hypothesis that the ability to actively represent and maintain context information is a central function of working memory and that a disturbance in this function contributes to cognitive deficits in schizophrenia, the authors modified 3 tasks—the AX version of the Continuous Performance Test Stroop, and a lexical disambiguation task—and administered them to patients with schizophrenia as well as to depressed and healthy controls. The results suggest an accentuation of deficits in patients with schizophrenia in context-sensitive conditions and cross-task correlations of performance in these conditions. However, the results do not definitively eliminate the possibility of a generalized deficit. The significance of these findings is discussed with regard to the specificity of deficits in schizophrenia and the hypothesis concerning the neural and cognitive mechanisms that underlie these deficits. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Verbal processing deficits in schizophrenia.

The authors reported that a subgroup of schizophrenic patients performed well on a tone serial position task but was impaired on an auditory word serial position task (Wexler, Stevens, Bowers, Cerniak, & Goldman-Rakic, 1998). This study assessed 30 schizophrenic and 32 controls (matched for comparable tone discrimination) on 4 versions of the verbal serial position tasks and 2 tone serial position tasks. Patients performed poorly on all verbal tasks but performed comparably to controls when tones served as stimuli. Proactive interference and visual presentation further compounded the verbal deficits. Deficits persisted with pronounceable nonword stimuli. These findings provide evidence of specific deficits in language-related processing, although the authors could not rule out the possibility that the differential effects that were observed between the tone and word tasks, and particularly among the verbal tasks, may result from differing discriminating power of the different tests. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Task set switching in schizophrenia.

The authors used a task-switching paradigm to investigate set shifting ability in schizophrenia. This paradigm included 2 choice reaction time (RT) tasks: up–down and right–left. Switching tasks were associated with costs (i.e., longer RT in task-switch trials than in task-repetition trials); patients responded more slowly than controls and suffered greater switching costs, were as efficient as controls in engaging in an upcoming task set, and were faster than controls in disengaging from the previous task set. There were indications that patients quickly forgot what each keypress indicated, making it necessary for them to acquire response meaning information anew in each trial. To test this notion, the authors subsequently tested normal participants in conditions in which response meaning information needed to be acquired anew in each trial. These participants produced a pattern of switching costs resembling that of patients. Results suggest that set switching difficulties in schizophrenia, as exhibited in the present paradigm, reflect poor memory for task context information. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Working and strategic memory deficits in schizophrenia.

Working memory and its contribution to performance on strategic memory tests in schizophrenia were studied. Patients (n?=?18) and control participants (n?=?15), all men, received tests of immediate memory (forward digit span), working memory (listening, computation, and backward digit span), and long-term strategic (free recall, temporal order, and self-ordered pointing) and nonstrategic (recognition) memory. Schizophrenia patients performed worse on all tests. Education, verbal intelligence, and immediate memory capacity did not account for deficits in working memory in schizophrenia patients. Reduced working memory capacity accounted for group differences in strategic memory but not in recognition memory. Working memory impairment may be central to the profile of impaired cognitive performance in schizophrenia and is consistent with hypothesized frontal lobe dysfunction associated with this disease. Additional medial-temporal dysfunction may account for the recognition memory deficit. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Task difficulty and the efficiency of muscular activity.

Hypothesized that intensity and organization of muscle activity are functions of S's expectation of difficulty of a task. Task difficulty was varied for 15 20-40 yr. old instructors and undergraduates by preparing S for holding heavy and light weights, respectively. The difficult task consisted of holding a 41-lb weight following 30 sec. of holding a 19-lb weight. The easy task was holding a 6-lb weight following 30 sec. of holding the 19-lb weight. Electrical activity of the following muscles of the right (active) arm was measured: biceps brachii, brachialis, brachioradialis, flexor carpi ulnaris, and triceps. During the holding of the middle range weight, muscle activity was lower in preparation for the heavy weight than for the light weight, but there were no significant changes in the organization of muscle activity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Task difficulty as a moderator of long-range prediction.

Used longitudinal studies of career progress in terms of salary or position attainment to test J. Weitz's (see 40:11) hypothesis that personality variables should predict early in time for high-aptitude Ss and late in time for low-aptitude Ss. Results for 396 maintenance technician trainees followed-up over a 9-yr period and 103 sales trainees followed up over an 11-yr period supported the hypothesis. The Ascendancy scale of the Gordon Personal Profile was found to predict the progress criterion at least 3 yr. earlier for those high, compared to those low on initial training performance. The predictability for low-aptitude Ss appeared to be more complex suggesting that the task, "getting ahead" contained additional personality correlated elements for the latter group. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Emotion deficits in schizophrenia: Timing matters.

The past two decades of research on emotional response in schizophrenia has demonstrated that people with schizophrenia do not have a marked deficit in reported emotional experience in the presence of emotionally evocative stimuli. However, the extent to which people with schizophrenia maintain their emotional state to guide future behavior remains a largely unexplored area of investigation. In the present study, we tested hypotheses about whether people with schizophrenia maintained their emotional state in the absence of emotionally evocative stimuli. In addition to reported emotional experience, we measured startle response magnitude both during the viewing and after the offset of emotional pictures to assess whether people with schizophrenia (n = 31) and without schizophrenia (n = 28) differ in their patterns of immediate response to emotional pictures and in their patterns of maintenance of these responses. Our findings indicated that people with and without schizophrenia did not differ in their self-report or startle response magnitude during presentation of emotional pictures. However, healthy controls maintained these responses after the stimuli were removed from view, but people with schizophrenia did not. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Deficiencies in the detection of cognitive deficits.

Numerous studies purport to show that cardiopulmonary bypass (CPB) surgery is associated with persistent postoperative cognitive decline. In J. R. Keith et al. (2002), the authors argued that reports of post-CPB cognitive declines have often been quantified using data analysis methods that were based on tenuous assumptions and overlooked problems associated with familywise Type I errors. Four peers who are recognized for their expertise in neuropsychological outcomes research evaluated the arguments developed in the J. R. Keith et al. article, critiqued the study presented in that article, and offered suggestions for how to investigate whether cognitive decline occurs reliably after CPB. In this reply article, the authors respond to the open-peer commentaries made regarding the J. R. Keith et al. study. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Interventions for cognitive deficits in brain-injured adults.

Reviews the state of the art with regard to interventions for disturbances in information processing following brain damage. Emphasis is placed on recent advances in techniques and issues vital to establishing such interventions as credible, legitimate types of treatment. Two series of studies are noted, one of which examines the treatment of spatial neglect in right-brain-damaged people and the other of which cites the development of modules for the improvement of different skills impaired in brain-damaged people. Of particular importance are the development of experiences and knowledge around (a) ecologic issues, (b) remediation in different population groups, (c) emotional problems and their management, and (d) development of an articulated theory of rehabilitation. (49 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Problems in the measurement of cognitive deficits.

Considers that artifacts cloud the findings in a majority of the studies on differential cognitive deficit because of differences in discriminating power of tasks coupled with generalized deficit of patients. With 2 tests of differing reliability, the test with the higher reliability will yield greater performance deficit for the less able Ss. The advisability, in studies of differential cognitive deficit, is discussed of matching tasks on reliability, shape of the distribution of scores, and mean, variance, and shape of the distribution of item difficulty, using normal Ss alone as a standardization group. Data from a study with 49 severely disturbed schizophrenics and 206 normals is presented. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Delusional thinking and cognitive organization in schizophrenia.

A delusion can be conceptualized as a form of cognitive reorganization; according to this interpretation a delusion serves to integrate into a meaningful and acceptable whole data which otherwise would be anxiety provoking. On the assumption that the utilization of delusions is representative of a generalized cognitive technique for dealing with ambiguous inputs it was hypothesized that delusional schizophrenics should manifest a stronger tendency to integrate ambiguous stimuli in a laboratory situation than nondelusional schizophrenics. To test the hypothesis 24 delusional and 25 nondelusional schizophrenics were compared on the McGill Closure Test. The results supported the hypothesis. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Self-editing deficits in schizophrenia: A word-association analogue.

Made contrasting predictions to differentiate a 1- from a 2-stage model of word-association performance in schizophrenia. 24 schizophrenics and 24 normals provided word associations in response to (a) "free" vs. "idiosyncratic" instructions, and (b) stimulus words that typically elicit either a strong dominant or several weak associations. Results confirm the 2-stage model: under idiosyncratic instructions, schizophrenics produced more common associations than normals. Findings were consistent with 2 assumptions pertinent to the 2-stage model: schizophrenics (a) sample from an underlying repertoire of nondeviant associations; and (b) are deficient in the ability to edit out sampled but situationally inappropriate associations, whether common or unusual. (18 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The contribution of metamemory deficits to schizophrenia.

A number of recent studies have demonstrated that individuals with schizophrenia display knowledge corruption; that is, they hold false information with strong conviction. This aberration in metamemory is thought to stem from poor memory accuracy in conjunction with impaired discrimination of correct and incorrect judgments in terms of confidence. Thirty-one participants with schizophrenia, along with 61 healthy control participants and 48 control participants with other psychiatric conditions, participated in a computerized source memory task. Whereas no differences in memory accuracy were observed between the group with schizophrenia and the group with other psychiatric diagnoses, knowledge corruption was specifically impaired in those with schizophrenia. Schizophrenia participants showed a significantly decreased confidence gap: They were more confident in errors and less confident in correct responses relative to those in the control groups. Knowledge corruption is theorized to be a potential risk factor for the emergence of delusions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attention deficits in childhood-onset schizophrenia: Reaction time studies.

The hypothesis of continuity between childhood-onset and adult schizophrenia was tested by comparing the performance of 15 patients with childhood-onset schizophrenia and 52 age-matched controls on 2 reaction time paradigms that have been used to study adult schizophrenia. On simple reaction time to tones with regular and irregular preparatory intervals of 2, 4, and 8 s, patients showed greater effects of the length of the preparatory interval in the regular condition and greater effects of the preparatory interval (girls only) and the preceding preparatory interval in the irregular series. On simple reaction time to random lights and tones, patients were faster on sequences than cross-modal sequences compared with controls. Overall, patients were much slower than controls in both paradigms. The results suggest similar attention dysfunction as is found in adult schizophrenia and thus are consistent with the continuity hypothesis. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Task difficulty, cardiovascular response, and the magnitude of goal valence.

Studied the impact of expected task difficulty on anticipatory cardiovascular (CV) responsiveness and the anticipatory reactivity under difficult task conditions in 64 female undergraduates. Ss performed an easy, moderately difficult, or extremely difficult memory task to earn a small incentive for good performance. CV and subjective measures were taken immediately prior to task performance. Both systolic blood pressure (SBP) responses and ratings of goal attractiveness were nonmonotonically related to expected task difficulty, with the most pronounced SBP elevations and highest goal attractiveness in the moderately difficult task condition. CV response measures revealed a strong positive association between systolic and diastolic pressure (but not heart rate) change in the easy condition, positive relationships among measures in the moderately difficult condition, and no significant correlations in the extremely difficult condition. Subjective measures of arousal were not affected by task difficulty. Principal findings are discussed in terms of J. W. Brehm's theory that motivation varies as a nonmonotonic function of the difficulty of goal attainment. Intercorrelations among CV response variables are considered in terms of their possible indication of the mechanisms underlying blood pressure changes associated with variations in motivation. (35 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attentional asymmetry in schizophrenia: Disengagement and inhibition of return deficits.

This research examined 2 components of visual orienting in medicated schizophrenia patients: the validity effect and the inhibition of return (IOR). In the 1st experiment, patients showed the expected asymmetry in orienting attention, that is, larger validity effect in the right visual field than in the left. However, this asymmetry was due to a deficit in facilitatory processes rather than a disengagement deficit. In addition, patients showed a deficit in IOR. In the 2nd experiment, a 2nd central cue for summoning attention, explicitly, back to the center was used. In this experiment, normal IOR in schizophrenia patients was found. Because it was shown that schizophrenia patients do not have a disengagement deficit, IOR possibly could not be observed because of the increased facilitation in that location. It was proposed that the abnormality in visual attention in schizophrenia is due to a deficit in inhibitory processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Word and tone working memory deficits in schizophrenia

BACKGROUND: Verbal memory deficits have been reported in many studies of patients with schizophrenia. We evaluated the specificity of these deficits by comparing patients and control subjects on several verbal and nonverbal auditory memory tests. METHODS: Performance of stable, medicated outpatients with DSM-III-R diagnoses of schizophrenia (N = 38) was compared with that of healthy subjects (N = 39) on a word list immediate recall task, tone delayed discrimination tasks, and word and tone serial position tasks. Before memory testing, patients were divided into 2 groups based on their ability to perform normally on a screening test requiring pitch discrimination and sustained attention. RESULTS: The nonverbal tests were more difficult for control subjects than the verbal tests. Despite this, patients who performed normally on the screening test of perception and attention performed normally on both nonverbal tests but had highly significant deficits on both verbal tests (P<.001 and P = .02). Patients who performed poorly on the screening test had highly significant performance deficits on all the memory tests. CONCLUSIONS: One subgroup of patients with schizophrenia has a selective deficit in verbal memory despite normal motivation, attention, and general perceptual function. Another group has deficits in multiple aspects of cognitive function suggestive of failure in early stages of information processing.