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Biomedical subjects

P Goolkasian

Publications and source records attributed to P Goolkasian.

At least 19 recordsLinked to original sources
PubMed2001

Location constancy and its effect on visual selection.

The present study investigated how location constancy influences selective attention to a cued location. The relative effectiveness of target/distractor distance and target/distractor compatibility were studied under covert and overt attention conditions. Experiment 1 measured reaction time and error rates to a scaled target letter that appeared at varied locations from 0.62 to 20 deg. Experiments 2 and 3 looked at covert/overt attention when the target location was fixed rather than varied within a block of trials. To provide a comprehensive assessment of the two primary variables across location constancy conditions, effect sizes for these results as well as for related past research (Goolkasian, 1999; Goolkasian and Tarantino, 1999) are presented. The findings suggest that the location of the target (foveal vs peripheral) does not influence attentional patterns as much as the consistency of its location. When a target appears at varied locations from trial to trial, distractor compatibility effects are in general stronger than the effect of target/distractor distance. However, the relative importance of these two variables reverses when the presentation location of the target is fixed at a constant location.

Form Perception↗
PubMed2001

A Web site in cognitive science.

A Web site (http://web2-pc.uncc.edu/cogsci) has been established to support an interdisciplinary course in cognitive science. The modules include introductory reading material, interactive exercises/virtual laboratory, and pointers to existing material on the Web. Our approach to using the Web in support of instruction differs from distance learning initiatives because it is centered on an instructor and classroom experiences. The Web-based modules are used to supplement classroom lectures and provide an interdisciplinary perspective.

Cognitive Science↗
PubMed2000

Pictures, words, and sounds: from which format are we best able to reason?

The effect of presentation format on reasoning was studied with a sentence verification task. Background information was presented in single-format and combined conditions that included pictured, printed, or spoken versions of the stimulus items. In Experiment 1, a test sentence appeared together with the background at varied stimulus onset asynchronies, to study how format influences the acquisition of the stimulus information. In Experiments 2 and 3, however, the test sentence followed the presentation of the background, to test the effect of format on memory. Reaction time responses to the test sentences showed a consistent picture advantage. However, when participants responded to materials stored in memory, both pictured and spoken formats provided quicker responses in comparison to printed words, and the format difference was smaller than when materials were readily available on the screen. Multimedia presentations, when compared with single-format conditions, did not provide additional benefits.

Decision Making↗
PubMed1999

Development of the Neck Pain and Disability Scale. Item analysis, face, and criterion-related validity.

STUDY DESIGN: The development and testing of a new comprehensive measure of neck pain and disability, the Neck Pain and Disability Scale. OBJECTIVES: To provide an initial evaluation of the Neck Pain and Disability Scale's reliability and validity. SUMMARY OF BACKGROUND DATA: Although several measures exist for generalized pain and disability, none is specific for neck pain. More specific measurements should improve assessment of treatments and clinical research aimed at cervical pain syndromes. METHODS: The Neck Pain and Disability Scale was designed using the Million Visual Analogue Scale as a template and consists of 20 items that assess neck pain. In this study, 100 patients with neck pain, 52 patients with lower back and leg pain, and 27 pain-free volunteers were rated by the Neck Pain and Disability Scale. In addition, a subset of the 47 patients with neck pain were rated by several other established psychometric instruments. RESULTS: An item analysis showed a high degree of internal consistency among the 20 items on the Neck Pain and Disability Scale (r = 0.93), and face validity was established by comparing patients who had neck pain as well as lower back and leg pain with a pain-free group. The Neck Pain and Disability Scale scores correlated with the Oswestry Disability Questionnaire, the Pain Disability Index, and psychological measures of depression and neuroticism. CONCLUSIONS: The results suggest a highly reliable instrument for evaluating neck pain with at least four underlying dimensions. Further work to address the predictive validity of this new tool are under way.

Adult↗
PubMed1999

Retinal location and its effect on the spatial distribution of visual attention.

A series of studies tested for distractor compatibility effects across wide target/distractor distances (0.6 degree to 20 degrees of visual angle). The effects of precue condition, constant/varied target location, horizontal/vertical distractor distance, and foveal/peripheral presentation were studied. Results show strong compatibility effects across wide distances when distractors are at peripheral retinal locations. When both stimuli were presented at the same peripheral location in opposite hemifields, compatibility effects were evident within an area of at least 2.5 degrees of visual angle. In contrast, when foveally placed distractors were used, compatibility effects were found primarily with target letters positioned near. The findings suggest that distance effects are not homogeneous across retinal location.

Adult↗
PubMed1998

A randomized, double-blind, prospective pilot study of botulinum toxin injection for refractory, unilateral, cervicothoracic, paraspinal, myofascial pain syndrome.

STUDY DESIGN: In a randomized, double-blind study, two dosage strengths of botulinum toxin type A were compared with normal saline injected into symptomatic trigger points in the cervicothoracic paraspinal muscles. OBJECTIVES: To compare the effect of botulinum toxin type A injections with that of normal saline to determine the former's usefulness in the management of neck pain and disability. SUMMARY OF BACKGROUND DATA: The results of several studies have suggested that botulinum toxin type A may reduce pain associated with myofascial pain syndromes. METHODS: Thirty-three participants were divided randomly to receive either 50 or 100 units of botulinum toxin type A, or normal saline. Patients were re-evaluated over a 4-month period by assessment of their pain and disability and pressure algometer readings, and then offered a second injection of 100 units of botulinum toxin type A. RESULTS: All three groups showed significant treatment effects as measured by a decline in the scores on the Neck Pain and Disability Visual Analogue Scale and an increase in the pressure algometer scores. Group differences were apparent only when the authors considered the number of patients who were asymptomatic as a result of the injections. CONCLUSIONS: Although no statistically significant benefit of botulinum toxin type A over placebo was demonstrated in this study, the high incidence of patients who were asymptomatic after a second injection suggests that further research is needed to determine whether higher dosages and sequential injections in a larger cohort might show a botulinum toxin type A effect.

Adult↗
PubMed1998

Evaluation of multimodal treatment program for fibromyalgia.

A quasi-experimental design was used to assess a multimodal pain treatment program for female patients with fibromyalgia to ascertain immediate and long-term effects. Laboratory and self-report pain measures together with psychological measures were obtained from patients who were tested up to 6 months after treatment. Comparison data were also obtained from fibromyalgia patients who failed to qualify for the treatment program because of insurance coverage. Immediate and long-term treatment effects were evident with the psychological measures and the subjective pain measures but not with the laboratory pain measures. Participants who attended the month-long multimodal program achieved significant and positive changes on most of the outcome measures. However, relapse prevention must be addressed.

Activities of Daily Living↗
PubMed1997

Size scaling and spatial factors in visual attention.

This study investigates the effect of the visibility of near and far letter distractors on target processing by scaling the size of the distractor letters to compensate for changes in resolution across the visual field. In Experiment 1, scaled and unscaled distractors were presented at varied stimulus onset asynchronies. Results showed that scaling the size of distractor letters in relation to their distance from the target was effective in producing strong compatibility effects. Scaled distractors presented prior to, or simultaneously with, the target were found to interfere with target processing whether they were near or far from the target. Experiment 2 used scaled distractors and varied the presentation location and the amount of time for processing prior to the presentation of the target. Compatibility effects were found to vary by location and by the exposure duration of the distractor. The finding of distance effects at far locations supports a space-based visual-attention mechanism with a wide attention beam (Steinman, Steinman, & Lehmkuhle, 1995).

Adult↗
PubMed1996

Picture-word differences in a sentence verification task.

Effects of picture-word format were investigated with four problem-solving items. In Experiment 1, picture-word input was presented for 8 sec followed by a test sentence that included verbatim and inference statements. Subjects made a true/false reaction time to the test sentence. In Experiment 2, the input remained on the screen while the test sentence was presented with varied stimulus onset asynchronies from 0 to 1,000 msec. Results showed that responses to pictures were faster than responses to words, and the format effect was larger with inference than with verbatim sentences. The picture advantage seemed to be due to the nature of the input and how information is extracted from it. The findings are discussed within the context of text-processing theories (Glenberg & Langston, 1992; Larkin & Simon, 1987).

Adult↗
PubMed1994

Size scaling and its effect on letter detection.

Two ways of scaling letter size across eccentricity were investigated in a choice reaction time (CRT) task. Experiments 1 and 2 tested cortical magnification theory (M-scaling), while Experiment 3 used scaled sizes drawn from Anstis's regression formula (A-scaling). Experiment 4 compared both scaling techniques, together with the effect of exposure duration and the absolute size of the foveal letter. Results showed that scaling effectiveness improved when large rather than small foveal letters were used. A-scaling with a large foveal letter provided a good fit for the data at parafoveal locations, but underestimated the letter sizes needed at large eccentricities. M-scaling with a large foveal letter size produced CRTs that were independent of eccentricity. Exposure duration did not substantially affect performance.

Fixation, Ocular↗
PubMed1990

Letter identification and lateral masking in dyslexic and average readers.

Lateral masking and letter identification in dyslexic and average readers were investigated with a methodology that corrected for some of the weaknesses of the Geiger and Lettvin studies (1986, 1987). Target letters were presented alone or embedded within three-letter arrays at retinal locations from 0 degrees to 15 degrees to the right or left of a fixation point. A foveal letter, which was the same as or different from a target letter, appeared as a distractor, and comparisons were made between scaled and unscaled stimuli. Dyslexic readers were found to be better than average readers at detecting scaled letters embedded in an array in some of the peripheral locations tested. Unlike the results of Geiger and Lettvin, however, this finding of better letter detection in the periphery by dyslexics was limited to selected conditions of the study. Reading groups were also found to differ in responding to the foveal distractor in the letter task. Detection of letters by average readers was affected by the type of distractor, but this variable was not found to influence the dyslexic readers. These findings suggest some differences between dyslexic and average readers in attention to stimuli presented at multiple locations in the visual field.

Adult↗
PubMed1987

Ambiguous figures: role of context and critical features.

Context and attention to critical features as factors in determining the perceptual organization of ambiguous figures were investigated in the present two studies. In the first study, a fixation point directed attention to a critical or to a neutral feature of an ambiguous figure. Placement of the fixation point on different features of an ambiguous figure did not affect the figure-ground organization of the figure, but it did influence the speed of the identification response. In the second study, presentation of an ambiguous figure was preceded by a biased figure or by features of the figure. Results indicated that the interpretation of the ambiguous figure was overwhelmingly influenced by the advanced presentation of a biased drawing but only slightly influenced by the advanced presentation of a critical feature. These findings support analysis-by-synthesis (Neisser, 1967) as an explanation of the perception of ambiguous figures over other contemporary attention theories.

Attention↗
PubMed1984

Picture-digit differences in processing clock times.

Clock times displayed as digits and as clockfaces were used as stimuli in a series of experiments that tested the hypothesis that a common numerical code was used for processing clock times. Whether the task involved reading times or making comparative judgments of early/late or same/different, digits were always processed faster than clockfaces . The size of the format effect varied, however, with the processing demands of the task and with times at specific locations on the clockface . Also, automatic processing of times presented as clockfaces interfered with comparative judgments made with digits, but digital distractors were not found to interfere with judgments made to times as clockfaces . The findings are discussed within the context of picture-word differences in rate of access to articulatory and semantic codes. Conclusions are also made regarding the relative efficiency of displaying times digitally and in the form of clockfaces .

Attention↗
PubMed1981

Retinal location and its effect on the processing of target and distractor information.

Two experiments were conducted to study the perceptual facilitation and inhibition that occurs between foveal and parafoveal or peripheral regions of the eye. Experiment 1 used a Stroop task to compare color detection latencies of foveal and parafoveal targets. The target and distractor components of the Stroop stimuli were separated and presented with varied stimulus onset asynchronies. Experiment 2 used a Stroop-like task to replicate and extend the findings into the visual periphery. Subjects were found to process foveally presented distractor information while attending to targets presented in parafoveal or peripheral regions of the eye. Distractor information that was incompatible was suppressed while compatible information was used to facilitate target processing. When the targets were presented foveally along with the distractor information, subjects appeared to automatically process the distractor information. The findings are discussed within the framework of past studies that presented subjects with competing tasks across retinal location. The implications of these findings to a two-process theory of attention are also considered.

Attention↗