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Biomedical subjects

H Babkoff

Publications and source records attributed to H Babkoff.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1980

Grammatical decision time and visual hemifield stimulation.

An experiment was performed to study grammatical decision time to three-letter Hebrew verbs and nouns presented to the right or to the left visual hemifield. Decision time was measured by the subject's manual response involving the movement of the index finger from the middle one of three electronic contact keys, to the right key to indicate the appearance of a verb, and to the left key to indicate the appearance of a noun. A comparison was also made of two response conditions, right hand responding versus left hand responding. The results indicate a greater number of errors in responding to verbs than to nouns, but no difference in accuracy between right visual field (RVF) stimulation and left visual field (LVF) stimulation. In contrast, the results indicate that grammatical decision time to Hebrew verbs is shorter than to nouns for all conditions of stimulation and response. Decision time to verbs appearing in the right visual field (RVF) is shorter than to verbs appearing in the left visual field (LVF). Consequently, the difference in decision time between verbs and nouns is greater for RVF stimulation than for LVF stimulation. There is no difference in decision time for stimulation of the RVF or LVF by nouns. Responding hand also does not affect grammatical decision time to either verbs or nouns in either RVF or LVF stimulation.

Choice Behavior↗
PubMed1980

Temporal sequence discrimination of dichotic tones: the effect of frequency.

The present study was designed to investigate the effect of stimulus frequency on the ability to discriminate the temporal sequence of two 250 ms-duration dichotic stimuli. Dichotic stimulus pairs of three frequencies were tested, 493 Hz, 988 Hz and 3982 Hz, using a three-alternative forced-choice design. The results indicate that frequency does not affect the form, the slope or the location along the abscissa of the discrimination functions. All functions reached 67% discrimination level with a dichotic temporal asymmetry of approximately 40-45 ms.

Auditory Perception↗
PubMed1977

Electrocutaneous input-output functions: magnitude estimation and reaction time.

An experiment was conducted on the effect of electrocutaneous stimuli on the generation of two types of input-output functions, and their relationship to each other. The data indicate that increasing electrocutaneous stimulus intensity results in a monotonic growth of magnitude estimation and a negatively decelerating decrease in reaction time. Reaction time approaches an asymptote at high intensities. The dynamic range of reaction time (RT), i.e., the RT which decreases as a function of increases in intensity was subtracted from the asymptotic reaction time (RTmin) for the subsequent analyses. The two-parameter power function provides a better fit for magnitude estimation as well as for RT--RTmin as a function of stimulus intensity than either a two-parameter linear or log-linear equation. When RT--RTmin is plotted as a function of magnitude estimation on a log-log scale, the data are within 4% of the predicted linear equation with a slope of --1, with no significant nonlinear components. If these data are plotted on a linear-linear scale, the linear coefficient is 31% steeper than --1, and a significant nonlinear component is present.

Electric Stimulation↗
PubMed1977

Effects of light-deprivation on visual discrimination in adult rats.

The effects of light-deprication on light flux discrimination by adult rats were tested by a conditioned lick-suppression technique. Total binocular light-deprication for a period of 37-38 days leads to decreased discrimination of the CS (a reduction of 0.64 log units in illumination) by adult rats. The argument is made that these data indicate sensory deficit in the adult animals resulting from binocular light-deprivation.

Animals↗
PubMed1977

Light-deprivation and light-adaptation: a preliminary study.

Preliminary data are presented on the effect of light-deprivation on the b-wave evoked in an eye exposed to and during recovery from a 500 msec duration conditioning pulse. The data indicate that the greatest differences between the amplitude of the b-wave evoked in the normal and light-deprived eyes are found for the dark-adapted retina. If the normal and light-deprived eyes are exposed to a conditioning pulse, the differences in b-wave amplitude between them are reduced. There is an increase in the difference between the b-waves evoked in the normal and light-deprived eyes as a function of time after the offset of a conditioning pulse. Latency of the b-wave evoked in the light-deprived eyes is not longer than b-wave latency in the normal eyes.

Adaptation, Ocular↗