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131 patients with lymphoproliferative disorders were classified as having typical Chromic Lymphocytic Leukaemia [CLL], atypical CLL, Chromic Lymphocytic Leukaemia/Prolymphocytic Leukaemia [CLL/PL] or Non-Hodgkin's Lymphoma [NHL] using immunophenotyping and morphology. The incidence of trisomy 12 (+12) in each of the groups was ascertained using fluorescent in situ hybridization. Trisomy 12 was found to be rare in the typical CLL group (<3%) and more common in the atypical CLL (22%), CLL/PL (40%) and NHL (43%) categories. The low incidence of +12 in the typical CLL group is most likely due to our adherence to strict inclusion criteria to ensure other similar lymphoproliferative disorders, with a high incidence of +12, were excluded. This approach leads to more homogeneous disease categories and consequently may help to resolve issues such as the impact on survival of +12 in CLL.

Twenty-five subjects made graphic ratings of the perceived lateral position within the head of sounds presented through headphones. The stimuli were high frequency, pure tones and amplitude modulated sounds. For the amplitude modulated sounds, a 200 HZ modulation frequency was combined with carrier frequencies of 2200 HZ, 3200 HZ, 4200 HZ, and 5200 HZ, which were also the pure tone frequencies. Interaural level differences in the signals ranged from zero to 12 dB. The rate of lateralization was defined as the slope of the linear trend relating laterality ratings to interaural level differences. The rate of lateralization was found to be a decreasing function of frequency. The laterality ratings of amplitude modulated signals were nearly identical to those for pure tones. This result suggests that, for high frequency signals, conflicting temporal information that a source is centered is suppressed in favor of information from level differences that the source is off-center.

Twenty subjects made graphic ratings of the perceived laterality of amplitude modulated sounds that were presented through earphones. A 200 Hz modulation frequency was combined with carrier frequencies of 2200 Hz, 3200 Hz, 4200 Hz, and 5200 Hz. The modulator sinusoid was delayed to either ear by temporal intervals ranging from zero to 0.6 ms. A significant interaction of carrier frequency with the linear trend for interaural temporal disparity indicated that the slopes of laterality ratings on temporal disparity decreased with carrier frequency. A significant interaction of carrier frequency with the difference in ratings for the 0.6 ms delays to the two ears indicated that the range in laterality ratings decreased with carrier frequency. The results indicate that the amount of laterality is a decreasing function of carrier frequency for high frequency sounds, which may be a consequence of greater weight being given to zero intensity difference as frequency increases.

In two experiments, 13 and 9 subjects estimated binocular brightness of targets of large visual extent. On each trial one eye was presented with a fairly intense luminance of 800 cd/m2, and the other eye with one of 12 luminances ranging from zero to 800 cd/m2. The first experiment, using ganzfeld stimuli (stimuli of uniform luminance that cover the entire visual field), produced a large amount of binocular brightness summation and very little Fechner's paradox, a decrease in binocular brightness that occurs when the luminances to the two eyes differ greatly. The second experiment, using a smaller target with very low spatial frequencies, produced greater Fechner's paradox than the ganzfelder, but more binocular summation and less Fechner's paradox than what is usually reported for small targets with abrupt contours. The results suggest a trade off between suppressive and summative mechanisms involving binocular cells that are spatially tuned. The trade off is controlled in the vector-sum model by the angle between vectors, which reflects the total inhibition in spatially tuned, binocular channels.

Some mathematical properties of coefficients of power functions were analyzed. The size of correlations between intercepts (the logarithm of the coefficient) and exponents depends on the choice of unit of measurement of the physical stimuli. When the mean of logarithms of a set of responses is uncorrelated with the exponent, the absolute size of the correlation between the intercept and the exponent increases as the geometric mean of the stimulus measures deviates from one. When the geometric mean is less than one, the correlation is positive, and when it is greater than one, the correlation is negative. Similar trends hold for a nonzero correlation between the exponent and the mean logarithm of a set of responses. The power of statistical tests of differences between mean intercepts also depends on the geometric mean of the stimuli. Power is reduced as the geometric mean deviates from one. Effects are illustrated with real data.

When a subject evaluates the duration of two simultaneous events, the perceived durations are combined in a nonlinear manner, whereas comparable evaluations of successive events yield linear combinations. Fifty-four subjects rated average durations of pairs of time intervals ranging from 0.5 s to 10.0 s. The intervals making up a pair were presented successively and simultaneously on separate occasions within the same presentation sequence. The order of data was consistent with models previously proposed for perceived average duration. A nonmetric analysis of the combined ordinal data from both conditions yielded a single set of measures of perceived duration with ratio-scale properties. The common scale for the two conditions is consistent with differences in results from simultaneous and successive monitoring of time intervals, stemming from differences in the way duration information is combined rather than how it is perceived. the derived scale is related to physical time by a power function with a 1.06 exponent.

Because nonmetric analyses of judged ratios and differences in sensory magnitude have yielded similar scales, some investigators have concluded that a single perceived relation underlies both judgment tasks. Issues rasied by this interpretation are considered in this article. Simulated data based on the assumption that subjects evaluate both perceived relations were computed for stimulus values used by Veit to investigate judgments of ratios and differences in grayness. A nonmetric analysis of both sets of simulated data in terms of a difference model yielded a solution such that each set of data was a weak monotonic transformation of the model's values, and the scale values were approximately linear with those obtained by Veit from empirical data. This result leaves open the question of whether one or two perceived relations underly the data. Ordinal properties of ratios and differences for a finite set are discussed together with their relation to systematic biases in psychophysical judgment tasks.

The relation between monocular and binocular brightness was examined. Clear evidence was found that the interaction between visual channels in binocular processing of brightness information implicates both an apparent averaging of monocular brightness when they are grossly different and a partial summation when they approach equality. A vector-sum model is shown to predict these properties. A nonmetric method was used to fit such a model to data from three experiments in each of which 15 subjects estimated brightness of binocularly fused targets. Magnitude estimation was used in two experiments, and cateogry ratings were obtained in the third experiment. When it was assumed only that subjects' responses were monotone with perceived brightness, estimates of the model's parameters from the data of the three experiments were almost identical, indicating that results from magnitude estimati;n and category rating can converge once nonlinear response functions are eliminated.

In previous studies, judgments of ratios and differences in subjective magnitude have yielded similar orders, consistent with a hypothesis that a single perceived relation underlies both judgment tasks. In the present research, 15 subjects estimated heaviness differences between 28 pairs of eight weights and each of 8 groups of 10 subjects evaluated heaviness ratios of eight variable stimuli with respect to a different standard stimulus. Presenting stimuli that were equally spaced on a cube-root scale of weight enhanced expected ordinal discrepancies between ratio and difference estimates, and employing independent groups for each standard stimulus in ratio estimation eliminated a possible bias due to varying standards within the presentation sequence. Differences in orders of ratio and difference estimates together with differences in scales obtained from non-metric analyses in terms of a difference model indicated that the judgments were based on two perceived relations that are ordinally consistent with arithmetic operations of ratios and differences. A ratio scale of heaviness was derived from the combined orders of subjective ratios and differences.