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Biomedical subjects

H Babkoff

Publications and source records attributed to H Babkoff.

At least 19 recordsLinked to original sources
PubMed1992

Selected problems of analysis and interpretation of the effects of sleep deprivation on temperature and performance rhythms.

One of the major methodological-analytic problems encountered by researchers in sleep deprivation involves the examination and analysis of the relationship between sleep loss and rhythmic influences on performance. The comparison of performance rhythms with physiological rhythms, e.g., body temperature, generated under the same conditions of sleep deprivation, has become an important means of testing for an endogenous source of the rhythmicity in the data and for clarifying the nature of the proposed oscillator system. Should the data sets be correlated before or after their separation into monotonic and rhythmic parts? Correlating the raw data without separating them into their components can yield negative results, while, in reality, some of the major underlying rhythms may be highly related. The example used in this chapter showed strong cross correlations of the circadian components of temperature and two performance tasks. Sleep deprivation is thus seen to interact with performance rhythms. This interaction is only revealed after the data are analyzed and broken into their component parts. This procedure leads to the conclusion that certain performance rhythms and temperature may share the same generating oscillators.

Body Temperature↗
PubMed1992

Meta-analysis of the relationship between total sleep deprivation and performance.

Studies consistently show that total sleep deprivation (TSD) and measures of performance are negatively correlated. However, an accurate quantitative summary of the relationship between these variables has not yet been reported. After collection of the data from 27 relevant studies, meta-analytic techniques were used to test several hypotheses. The correlations were found to be highest for TSD of greater than or equal to 45 h, speed rather than accuracy measures of performance, and work-paced rather than self-paced tasks. These findings are consistent with the "lapse hypothesis" that posits microsleeps during long hours of sleep deprivation.

Chronobiology Phenomena↗
PubMed1991

Monotonic and rhythmic influences: a challenge for sleep deprivation research.

There are both monotonic and rhythmic factors in the patterns of change seen in physiological, psychological, and performance variables during sleep deprivation. These monotonic and rhythmic factors can be orthogonal, or they may interact with each other, with various task variables, or both. The importance of separating the rhythmic from the monotonic factors and of elucidating their interactions is discussed. Experimental methods and types of analysis appropriate to evaluating these factors are examined, with special emphasis on the complex demodulation time series analysis applied to group or individual subject data. The discussion is accompanied by data illustrations. It is suggested that sleep deprivation research should be designed so as to generate physiological and behavioral data that include information on both monotonic and rhythmic factors, the nature and extent of their interaction, and how they interrelate with systematically manipulated independent variables.

Arousal↗
PubMed1991

Subjective sleepiness ratings: the effects of sleep deprivation, circadian rhythmicity and cognitive performance.

Computerized self-report sleepiness scales were administered before and after cognitive testing in a 72-hour sleep deprivation study. The cognitive test battery was administered every 2 hours and took approximately 1-1.25 hours. Two computerized measures of subjective sleepiness were used, one a visual analog scale, the other a Hebrew version of the Stanford sleepiness scale. The results indicated that both accumulated sleep loss, circadian and ultradian (2 cycles/day) factors were significant in determining subjective estimates of sleepiness. The extent of the differences between subjective sleepiness ratings before cognitive testing and after testing was dependent upon the phase of the circadian cycle. These differences were greatest at approximately 0200-0600 hours and least around 1000 hours. A second low point occurred at 1800-2000 hours. Analysis by complex demodulation of the individual subjects' sleepiness rating curves indicated that the amount of variance accounted for by the circadian component increased significantly after cognitive testing.

Adult↗
PubMed1990

The impact of cognitive interference on performance during prolonged sleep loss.

A study was conducted on the effects of off-task cognitions on performance during sleep deprivation. Subjects answered the Thought Occurrence Questionnaire, assessing their proneness to engage in off-task cognitions, and were deprived of sleep for 72 hours, during which they performed a variety of tasks including visual discrimination and three versions of a logical reasoning task in which cognitive load was varied systematically. In addition, every day subjects answered the Cognitive Interference Questionnaire, which taps off-task cognitions during the experiment. Results indicated that subjects who habitually engage in off-task cognitions performed worse during 72 hours of sleep loss than subjects who do not engage in such distracting activities. In addition, it was found that the engagement in off-task cognitions increased during the 72 hours of sleep loss and such an engagement was related to deficits in performance accuracy. The mechanisms of off-task cognitions and sleep loss underlying these effects are discussed.

Adult↗
PubMed1989

The effects of 72 hours of sleep loss on psychological variables.

A study was conducted on the effects of 72 hours of sleep loss and modified continuous operations on performance and psychological variables. This paper presents the results of self-report data of 12 subjects for the following psychological variables: sleepiness, affect, motivation, cognitive difficulties, and waking dreams. The relationship between the self-report measures and performance in a visual search and memory task is also examined. Most of the psychological variables are significantly affected by the number of days of sleep deprivation, all are significantly affected by hour of day; but only sleepiness, affect and motivation are also significantly affected by the interaction between these variables. The peak hours for self-reported psychological complaints are generally between 0400 and 0800, while the lowest number of complaints are usually reported in the afternoon/early evening, between 1600 and 2000. In addition, the results showed that (a) the amplitude of the circadian component of the psychological data increased over the period of sleep loss, and (b) psychological data were more highly correlated with a measure of general performance than with accuracy. The mechanisms of sleep deprivation underlying its effects on psychological and performance measures are discussed.

Adult↗
PubMed1989

Perceptual distortions and hallucinations reported during the course of sleep deprivation.

Subjects worked 30 to 45 min. of each hour for either 48 (n = 2) or 72 hr. (n = 8) without sleep. The frequency of reported visual task-related perceptual distortions and hallucinations showed both a linear increasing component and a strong circadian component. Perceptual distortions were most frequent in the late night-early morning hours (0400) and least frequent in the late afternoon-early evening hours (1600-2000).

Adolescent↗
PubMed1988

Lexical decision and visual hemifield: an examination of the RT-accuracy relationship.

Visual hemifield, stimulus duration and angle of eccentricity were manipulated using a lexical decision paradigm (discrimination of words from non-words). Lexical decision was measured by several dependent variables: reaction time, (RT); accuracy, d'; and beta. The results support the generalization of RVF superiority in a lexical decision task for parafoveal stimulation for three dependent variables, RT, accuracy and d'. No significant effect of any stimulus manipulation was found for beta. When RT is plotted as a function of accuracy, the data separate into two groups (one for words, one for non-words) each best described by a linear equation with negative slope. The implication of this analysis is discussed, and the hypothesis offered that the same basic process discriminates words from non-words in a lexical decision task, regardless of visual field, parafoveal angle of eccentricity or stimulus duration. Visual field is processed no differently from the other stimulus manipulations.

Adult↗
PubMed1985

Lexical decision, parafoveal eccentricity and visual hemifield.

The effect of the eccentricity of parafoveal stimulation on a lexical decision task was studied using stimuli presented to the two visual hemifield. Five-letter word and nonword stimuli were presented to three parafoveal locations ranging over 1 degree angle of eccentricity. Subjects responded manually. The results of the analyses indicated that the average RT to words was approximately 48 msec. shorter than to nonwords. The average RT to a stimulus presented to the RVF was approximately 11 msec. shorter than to a stimulus presented to the LVF. As parafoveal location became more eccentric, RT to all stimuli increased by approximately 37 msec. per degree of eccentricity. A very significant interaction was found between the visual hemifield stimulated and the direction of response to the type of stimulus presented (word/nonword).

Dominance, Cerebral↗
PubMed1985

Individual use of judgmental dimensions and hemispheric specificity.

The present study investigated the relationship of hemispheric functional specificity to a subject's use of judgmental dimensions when discriminating temporal and spatial visual stimuli using a multidimensional scaling (MDS) paired-comparison paradigm. The major purposes of the study were: To identify the judgmental dimensions used in discriminating unidimensional (temporal or spatial) and multidimensional (combinations of temporal and spatial parameters) stimuli presented to the two visual hemifields; to study the relationship of the use of judgmental dimensions to the visual hemifields; to investigate whether the use of judgmental dimensions in discriminating unidimensional stimuli can be used to predict their use in discriminating multidimensional stimuli. Subjects used two dimensions in discriminating the spatial and temporal unidimensional stimuli: A dimension whose scaling paralleled the physically interval-scaled stimuli; a dimension, in which the extreme values were located on one end of the scale, while the mid-values are located at the other end of the scale. There is significantly greater use of the spatial dimension when spatial stimuli are presented to the left visual field (LVF) then when presented to the right visual field (RVF). Conversely, there is significantly greater use of the temporal dimension when temporal stimuli are presented to the RVF then when they are presented to the LVF. Three perceptual dimensions were used to judge multidimensional stimuli: Spatial-to-temporal; stimulus quality; apparent movement. Two groups of subjects were identified who differed in their relative use of the temporally and spatially scaled unidimensional stimuli presented to the RVF. These two groups differed with respect to their relative use of a spatial-to-temporal dimension when multidimensional stimuli were presented to the RVF.

Cues↗
PubMed1984

Auditory brainstem evoked potential latency-intensity functions: a corrective algorithm.

The dynamic changes in the latency of the components of the auditory brainstem evoked potentials (ABEP) were analyzed and correlated with the psychophysical magnitude estimates of the stimuli evoking the potentials. This study included the reanalysis of the results originally reported by Pratt and Sohmer (1977, Electroencephalogr. Clin. Neurol., 43, 802-812), this time with correction for asymptote of the latency-intensity functions. The results of reanalyzing latency-intensity power functions have yielded exponents that were very similar across components, closer to the exponent of magnitude estimates and accounting for a higher amount of variance for all of the ABEP components. This procedure may also prove useful for clinical evaluation of auditory function.

Algorithms↗
PubMed1984

Sorting of hemifield presented temporal and spatial stimuli.

An experiment was performed, using a sorting task (choice reaction-time), to study the processing of stimuli, which differed along a temporal or a spatial dimension, presented to the right or to the left visual hemifield. The results indicate more accurate responses and shorter reaction times to a temporal stimulus when it appears in the right-visual-field than when it appears in the left-visual-field. Conversely, more accurate responses and shorter reaction times are found to a spatial stimulus when it appears in the left-visual-field than when it appears in the right-visual-field. In addition to this major interaction, three more interactions are found, all of which involve response direction and one or two other stimulus variables. The results are consistent with the hypothesized hemispheric functional specificity, i.e., that the initial processing of the temporal dimension of visual stimuli is performed better by the left hemisphere than by the right hemisphere and that the converse is true for the initial processing of the spatial dimension of visual stimuli.

Discrimination Learning↗
PubMed1983

Early prolonged light-deprivation in hooded rats: deficits in two visual discrimination paradigms.

Two types of experimental paradigms were used to study the effects of prolonged postnatal light-deprivation in hooded rats. The first experiment tested the effect of dark rearing on the acquisition of a light-flux discrimination using positive reinforcement discrimination; while the second experiment tested the effect of dark rearing on the acquisition and extinction of a conditioned emotional response (CER) using light-flux onset as a conditioning stimulus. Both positive discrimination and CER paradigms proved successful in revealing a deficit resulting from prolonged light-deprivation in hooded rats. These paradigms could differentiate a specific effect of light-deprivation on light-flux discrimination from general discrimination performance.

Animals↗
PubMed1983

Lexical decision time as a function of visual field and stimulus probability.

Two experiments were performed to study lexical decision time to word and non-word Hebrew trigrams as a function of stimulus probability, visual hemifield and responding hand. The results indicate that lexical decision time to words is shorter than to non-words. In addition, although decision time to words is significantly shorter with right hemifield stimulation than with left hemifield stimulation, decision time to non-words is the same whether they are presented to the right or left hemifield. Decision time to non-words decreases almost linearly as stimulus probability increases from 0.25 to 0.75, whereas decision time to words decreases in a concave manner apparently approaching an asymptote at a stimulus probability of 0.75. Responding hand is not significant as a main effect or in any interaction with any other variable. The data are discussed in terms of several models of hemispheric linguistic superiority.

Decision Making↗
PubMed1980

A comparison of psychiatric patients and normal controls on the integration of auditory stimuli.

Temporal processing of sensory auditory information was investigated in 27 psychiatric patients and 29 normal controls by measuring forced choice thresholds for the right ear to bursts of noise stimuli of three different durations-4, 32, and 128 msec. Psychiatric patients were found to be 5 dB less sensitive than normal controls. A subsequent analysis compared the normal controls with three subgroups of psychiatric patients differentiated according to symptom profile. Those psychiatric patients whose main symptoms were affective showed a shallower threshold duration integration function than did normal controls. Patients whose major symptoms were delusions of persecution and depersonalization showed a slightly steeper slope than normal controls, whereas patients whose major symptom were hallucinations and lack of insight showed the steepest slope.

Adolescent↗