Parametric aspects of tactile resolution

Three parameters of tactile resolution (area, force, and pressure of stimulation) were investigated in three experiments. A two-point discrimination task was presented by means of an electromechanical stimulator permitting precise control of all relevant stimulus variables. The results indicated a positive linear effect of area, a curvilinear effect of force, and no effect of pressure on the threshold for resolution of two tactile stimuli. The findings are in agreement with data on the influence of the same parameters in visual resolution.     

Spectral sensitivity of the Sooty mangabey

Purkinje shift and scotopic and photopic spectral sensitivity functions were determined for four Sooty mangabeys and five human controls using a flicker technique in a four-choice discrete trials task. Results-indicate a Purkinje shift similar in magnitude and frequency locus to that of human controls. Scotopic spectral sensitivity was almost identical to that of human controls, although both species showed reduced sensitivity relative to the standard CIE function, -at short wavelengths. Photopic spectral sensitivity disclosed enhanced sensitivity in the blue and reduced sensitivity (0.3–0.4 log units) in the red relative to human controls.     

Serial rote-learning: Incremental or all-or-none?

If the associative connections in a serial list are acquired in an all-or-none fashion, rather than gradually with every trial adding an increment of associative strength, then changing the serial order of the middle items in the list during the course of practice should have no effect on the rate of learning the list as a whole or even of the particular items that have been interchanged. Thirty subjects learned a serial list by the anticipation method. The middle items of the list were reversed in serial order approximately half-way through the number of trials required for mastery. The subjects took no longer to learn the list and made no more errors than did 30 control subjects for whom there was no change in serial order. The serial-position curves of the two groups were almost identical. It was also shown that the learning “curves” of single items in the series, when plotted for individual subjects do not reveal a gradually increasing probability of the correct response, but show instead a sudden jump on one trial from the chance guessing level to a level close to 100 per cent, correct responses. The results are consistent with a non-incremental theory of serial learning.     

Note on the “semantic” and the “absolute” concept of truth

Philosophical Studies -     

Reducing interference in forgetting

According to interference theories forgetting results from the intervention of extraneous associations which disturb the patterns built up during learning. It also seems that the period immediately following learning is critical for forgetting. The experiment which is described was carried out to investigate whether administration of the central-depressant drug nitrous oxide immediately after learning would reduce forgetting, since it had been shown to impair the formation of associations and ought therefore to reduce interference. This expectation was borne out, significantly less forgetting occurring when nitrous oxide was given than when air was given. A possible physiological basis, relating these results to those for sleep is discussed.     

The Predictive Validity of Parent and Teacher Reports of ADHD Symptoms

The objectives were to evaluate the ability of the Inattention and Hyperactivity–Impulsivity factors of the ADHD Rating Scale-IV to differentiate children with ADHD from a control group and to discriminate children with different subtypes of ADHD. Also, we sought to determine optimal cutoff scores on the teacher and parent versions of this scale for making diagnostic decisions about ADHD. In a sample of 92 boys and girls 6 to 14 years of age referred to a regional ADHD program, we assessed ADHD diagnostic status using categorical and dimensional approaches as well as parent- and teacher-report measures. Logistic regression analyses showed that the Inattention and Hyperactivity–Impulsivity factors of the ADHD Rating Scale-IV were effective in discriminating children with ADHD from a control group and differentiating children with ADHD, Combined Type from ADHD, Inattentive Type. Although both teacher and parent ratings were significantly predictive of diagnostic status, teacher ratings made a stronger contribution to the prediction of subtype membership. Using symptom utility estimates, optimal cutoff scores on the Inattention and Hyperactivity–Impulsivity scales for predicting subtypes of ADHD were determined.