Biomedical subjects

K R Krull

Publications and source records attributed to K R Krull.

6 recordsLinked to original sources

PubMed1996

Further validation of constructs from the selective reminding test.

The Selective Reminding Test (SRT) partitions recall into three classes. Short-Term Recall (STR), Random Long-Term Recall (RLTR), and Consistent Long-Term Recall (CLTR). Examination of conditional probabilities of delayed recall or recognition of individual words as a function of their memory status at the end of a standard 12-word, 12-trial test showed that Buschke's (1973) operational definitions of STR, RLTR, and CLTR have excellent predictive validity.

Adult↗

PubMed1995

A comparison of indices of premorbid intelligence in clinical populations.

Estimation of premorbid intelligence using the regression formula developed by Barona et al. (1984) was compared with prorated IQ's based on the higher of the Vocabulary or Picture Completion subtests from the WAIS-R. Actual and predicted premorbid IQ's of 50 brain-damaged patients were compared to those of 35 non-brain-damaged patient controls equated on age and education. For both groups, the Barona et al. (1984) formula produced mean IQ's close to 100, though greatly restricted the range. The prorated IQ's tended to be over-estimated in the patient control group, but not the brain-damaged group. Compared with the regression based formula, the distribution of these prorated IQ's was more consistent with the WAIS-R standardization sample.

Journal Article↗

PubMed1995

Interpretive significance of variability of performance on neuropsychological tests.

The interpretive significance of variability of performance on neuropsychological measures was investigated in groups of brain-damaged and non-brain-damaged subjects. The 39 brain-damaged subjects were matched on Full Scale IQ and age with 39 non-brain-damages subjects. The two groups failed to differ on a measure of level of performance, but did differ on variability of performance. The results were interpreted as providing support for the clinical utility of measures of variability of performance and indicating the need for additional investigation of such measures.

Journal Article↗

PubMed1994

Simple reaction time event-related potentials: effects of alcohol and diazepam.

Acute effects of alcohol and diazepam on reaction time (RT) and event-related potential (ERP) measures were examined in 108 healthy male volunteers. The subjects engaged in a simple RT task at two levels of stimulus intensity during baseline and treatment sessions. Lower stimulus intensity produced increased RT's, increased ERP peak latencies, and suppression of peak amplitudes. Moderate and high doses of alcohol, and high doses of diazepam produced increased RT's. Alcohol suppressed P100 and N100 amplitudes, while diazepam suppressed P100 amplitudes only. P100 amplitudes were correlated to RT's under baseline and treatment conditions. These results were taken as evidence for impaired stimulus detection during alcohol and diazepam intoxication, with both drugs influencing sensory-perceptual processes and alcohol alone influencing the degree of attentiveness.

Adult↗

PubMed1993

Simple reaction time event-related potentials: effects of alcohol and sleep deprivation.

The effects of two levels of alcohol intoxication and 30 hr of sleep deprivation on visual event-related potential (ERP) waveforms concomitant to simple reaction time (RT) were examined in 54 normal male subjects. In a previous study, we reported that alcohol and sleep deprivation each increased RT. At a 0.05 breath alcohol concentration (BAC), the combined treatments produced an additive increase in RT, whereas at a 0.08 BAC the combined treatments produced no increase beyond that seen with each alone. In this study we present the ERP findings. Sleep deprivation alone increased the latency of a 150 msec negative component (N1) of the ERP. Alcohol increased the latency of a 250 msec negative component (N2), but only in the absence of sleep deprivation. Furthermore, this increased latency of N2 was correlated with RT measures. These results suggested that sleep deprivation slowed initial stimulus detection, whereas alcohol slowed later processing and response activation.

Adult↗

PubMedDate not supplied

The influence of alcohol and sleep deprivation on stimulus evaluation.

The effects of alcohol and sleep deprivation on choice reaction time (RT) as a function of stimulus intensity, stimulus quality, and response compatibility were investigated. Fifty-four male subjects were assigned to one of three levels of alcohol (0.00, 0.07, or 0.10 BAC), and one of two levels of sleep deprivation (0 or 24 h). Stimulus intensity, stimulus quality, and response compatibility were varied (high or low), with RTs identified according to time on task. Significant main effects of each of the stimulus variables were present in baseline analysis, with low-level conditions producing longer RTs. Alcohol produced an overall slowing of RT. The combination of both treatments led to larger increases in RT for low stimulus quality. Sleep deprivation increased RT for high stimulus intensity. Alcohol increased RT for low stimulus intensity, but only when subjects were not sleep deprived. These results imply higher risk with degraded stimulus conditions, e.g., driving in settings of low visibility or at night.

Adult↗