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Murray T Maybery

Publications and source records attributed to Murray T Maybery.

11 recordsLinked to original sources
PubMed2006

Selective attention for negative information and depression in schizophrenia.

OBJECTIVES: Depression is a frequent feature of schizophrenia but the cognitive processes involved in its development and maintenance are unclear. Recent studies have shown that clinical depression is associated with faulty inhibitory mechanisms of selective attention for negative information. The current study examined whether patients with schizophrenia also have an attentional bias towards negative stimuli. The inhibitory processes of interference control and task-shifting abilities were also examined to assess whether patients would show a selective impairment. METHOD: Forty-three patients with schizophrenia and 24 healthy controls completed the Affective Shifting Task. RESULTS: As a group, schizophrenia patients did not show an attentional bias for negative material. However, those patients with high levels of depression demonstrated faster latencies when negative words were the targets, and higher depression scores were found to be associated with an increasing number of false alarms for negative words when they were not the targets. The results also showed that patients had impaired interference control but intact task-shifting abilities. CONCLUSIONS: Faulty inhibitory mechanisms of selective attention for negative information are not a general feature of schizophrenia but appear to be selective to those with a depressed mood. The results highlight the need for further studies examining the exact nature of the affective dysfunction in schizophrenia and the cognitive processes supporting negative emotions.

Adult↗
PubMed2005

Grouping in short-term memory: do oscillators code the positions of items?

According to several current models of short-term memory, items are retained in order by associating them with positional codes. The models differ as to whether temporal oscillators provide those codes. The authors examined errors in recall of sequences comprising 2 groups of 4 consonants. A critical manipulation was the precise timing of items within the groups, whereby temporal position (time from group onset) and ordinal position (number of items from group onset) were partially unconfounded. Errors that involve items migrating across groups should preserve within-group temporal position according to oscillator models, but should preserve within-group ordinal position according to nonoscillator models. Results from the intergroup errors strongly favored preservation of ordinal rather than temporal position.

Adolescent↗
PubMed2005

Neuropsychological studies of mild traumatic brain injury: a meta-analytic review of research since 1995.

A meta-analysis conducted by Binder, Rohling and Larrabee established a relationship between mild traumatic brain injury (TBI) and small reductions in cognitive functioning in individuals assessed more than 3 months post-injury. As a follow-up, this study summarized similar research that (1) was published since the previous meta-analysis, and (2) included data collected at any stage post-injury. An extensive literature search revealed 17 suitable studies from which effect sizes were aggregated. The overall effect size was g = 0.32, p < .001. Speed of processing measures had the largest effect, g = 0.47, p < .001. The merging of post-acute effect sizes with those reported in Binder et al.'s review yielded a nonsignificant result, g = 0.11. Time since injury was found to be a significant moderator variable, with effect sizes tending to zero with increasing time post injury.

Brain Injuries↗
PubMed2004

Context memory and binding in schizophrenia.

The current study aimed to provide evidence for the context-memory hypothesis, which proposes that schizophrenia is linked to a deficit in retrieving contextual information and in binding the different components of a memory together. A new task was developed in which memory for the content of events could be assessed in conjunction with memory for both source and temporal information. Forty-three patients with schizophrenia and 24 normal controls took part in the study. Patients were found to be less accurate in identifying the source and temporal context of events. Furthermore, whereas controls tended to identify correctly both source and temporal context of events, patients tended to have a more fractionated recollection of those events. The study provides support for the context-memory hypothesis by demonstrating that patients with schizophrenia show a fundamental deficit in binding contextual cues together to form a coherent representation of an event in memory.

Adult↗
PubMed2004

The long-term effects of mild head injury on short-term memory for visual form, spatial location, and their conjunction in well-functioning university students.

Research has suggested the presence of subtle long-term cognitive changes in otherwise well-functioning individuals who have previously sustained a mild head injury (MHI). This paper investigated the long-term effects of MHI on visual, spatial, and visual-spatial short-term memory in well-functioning university students. Sixteen students who reported having sustained a MHI were compared to 16 controls on tests of short-term memory (STM) for abstract polygons in haphazardly arranged locations. The three tests differed only in the requirements for recall (shapes for the visual task, locations for the spatial task, and the shapes in their respective locations for the visual-spatial task). MHI participants were selectively impaired on spatial memory, suggesting that tasks of spatial STM may be more sensitive, compared to tasks of visual STM, to the subtle long-term cognitive changes that may be present after a MHI.

Adolescent↗
PubMed2004

Effects of verbal labeling on memory for hand movements.

This study examined whether a secondary verbal shadowing task influences recall for hand movements. Descriptive verbal labels associated with hand postures (e.g., "fist", "palm") were presented auditorily, concurrent with video presentation of hand postures, and the participant was instructed to shadow the words aloud. In the congruent verbal labels condition, the words were matched with the hand postures shown, and in the incongruent condition, the labels and hand postures were unmatched. In Experiment 1 (N = 18), a computerized version of the Kaufman Hand Movements Test (KHMT), which involves three distinct hand postures, was performed under congruent and incongruent labels conditions, and baseline. For Experiment 2 (N = 18), the same format was applied to a hand movement span task, similar to the KHMT, but based on seven distinct hand postures. For both experiments, shadowing congruent labels enhanced serial recall, whereas shadowing incongruent labels reduced recall when compared to baseline. Thus memory for hand movements was affected by the content of the secondary verbal task, consistent with participants spontaneously using a verbal recoding and rehearsal strategy to support this form of memory, a strategy enhanced through the provision of appropriate labels.

Adolescent↗
PubMed2004

Temporal grouping in auditory spatial serial memory.

Grouping effects in serial recall have been widely studied with verbal stimuli, but hardly ever with spatial stimuli and not at all with auditory spatial stimuli. In Experiment 1, we examined the influence of combined temporal and pitch grouping on recall of the locations from which bursts of white noise were presented. Similar to findings in verbal studies, effects of the grouping manipulation were found in performance accuracy, in the nature of order errors, and in the timing of responses. Experiment 2 was designed to distinguish the role played by pitch grouping from that played by temporal grouping, through independent manipulation of the presence of a shift in pitch and that of a temporal gap. The results showed that the temporal grouping manipulation determined performance and the pitch grouping manipulation did not. Similarities between our findings and those of verbal studies, and implications for the understanding of serial memory are discussed.

Auditory Perception↗
PubMed2003

Inhibition in schizophrenia: association with auditory hallucinations.

The study investigated whether auditory hallucinations (AH) in schizophrenia are linked to a deficit in inhibition. Two tasks assessing the intentional suppression of cognitive events-the Hayling Sentence Completion Test (HSCT) [Neuropsychologia 34 (1996) 263] and the Inhibition of Currently Irrelevant Memories Task (ICIM) [Nature Neuroscience 2 (1999) 677]-were administered to 42 patients with schizophrenia and 24 normal controls. Presence and severity of symptoms in the patient group were examined using the Positive and Negative Syndrome Scale (PANSS). Patients performed significantly worse on the measures of inhibition compared to controls. More importantly, among patients, significant positive correlations were obtained between an index of AH severity (defined as an increase in frequency of AH on PANSS) and the number of type A errors on the HSCT and errors in the last three runs of the ICIM. An increase in AH severity was, therefore, associated with increasingly impaired control of intentional inhibition. Furthermore, no significant correlations were found between these indices of inhibition and either negative, general or positive symptoms (excluding AH scores).

Adult↗
PubMed2003

The hand movement test as a tool in neuropsychological assessment: interpretation within a working memory theoretical framework.

While the Kaufman Hand Movements Test (KHMT) is argued to be sensitive to cognitive impairment secondary to various forms of brain dysfunction in adults, it is unknown which cognitive processes it addresses. Dual-task research has employed tasks similar to the KHMT to determine whether such tasks assess (1) verbal or visuospatial memory, or (2) a proposed additional short-term memory component, movement memory. However findings consistent with both hypotheses have been reported. Experiment 1 involved 24 participants completing a hand movement task and a letter span task under articulatory suppression, finger movement and no interference conditions. Performance on both the hand movement task and letter span task was significantly reduced by articulatory suppression. In Experiment 2, 16 participants were administered the hand movement task and a Corsi span task under articulatory suppression, finger movement, spatial tapping, and no interference. Again, hand movement span was most reduced by articulatory suppression, in contrast to Corsi span which was most reduced by spatial tapping. Hand movement task performance was therefore assumed to rely upon verbal recoding strategies and thus the proposition of an additional component of movement memory was not supported.

Adult↗
PubMed2002

Grouping in short-term verbal memory: is position coded temporally?

The nature of the mechanisms that code item position in serial short-term verbal recall was investigated with reference to temporal grouping phenomena--effects that arise when additional pauses are inserted in a presented list to form groups of items. Several recent models attempt to explain these phenomena by assuming that positional information is retained by associating items with contextual information. According to two of the models--the Phonological Loop model (Hitch, Burgess, Towse, & Culpin, 1996) and the OSCAR model (Brown, Preece, & Hulme, 2000)--contextual information depends critically on the timing of item presentation with reference to group onset. By contrast, according to the Start-End model (Henson, 1998) and a development from it, which we label the Oscillator-Revised Start-End model (Henson & Burgess, 1997), contextual information is independent of time from group onset. Three experiments examined whether coding of position is time dependent. The critical manipulation was to vary stimulus-onset asynchrony from one group to the next in the same list. Lists of consonants were presented visually, but with vocalization in Experiment 1, auditorily in Experiment 2, and auditorily with articulatory suppression in Experiment 3. The pattern of order errors consistently favoured the predictions of the time-independent models over those of the time-dependent models in that across-group transpositions reflected within-group serial position rather than time from group onset. Errors involving intrusions from previous lists also reflected within-group serial position, thereby extending support for the time-independent models.

Adolescent↗