Correction of item-total correlations in item analysis

The biserial correlation between an item and the total test of which the item is a part tends to be misleadingly high when used in item analysis, since the item is included in the total test. Two formulas with correction for this overlap are derived and compared with Zubin's and Guilford's formulas. One of the new coefficients is invariant to test length.     

The relation between factor loadings and biserial correlations in item analysis

The first centroid factor loadings obtained from various interitem relations are compared with item discrimination indices commonly used in item analysis. Depending upon what type of matrix is factored, the factor loadings are shown to be related to point biserial and biserial correlations.     

Reliability and Validity Evaluation of the Psychopathy Checklist: Screening Version (PCL:SV) in Swedish correctional and forensic psychiatric samples

This study evaluated the structural reliability, construct-related validity, and cultural validity generalization of the Hare Psychopathy Checklist: Screening Version (PCL:SV) in a sample of more than 560 male and female Swedish forensic psychiatric treatment patients, forensic evaluation patients, and criminal offenders. Structural reliability was excellent for most indices. PCL:SV scores were higher for males than females for total and Part 1 scores (interpersonal/affective features) but not for Part 2 (behavioral features). With some exceptions, PCL:SV scores were meaningfully related to aggression to others, a measure of risk for violence, substance use problems, personality disorder (positive), and psychosis (negative). Correlations between PCL:SV and aggression were larger for females than males, although the difference was smaller when personality disorder was held constant. The structural reliability and pattern of validity coefficients were comparable in these Swedish samples to other non-North American samples. Implications for the cross-cultural manifestation and correlates of psychopathy are discussed.     

Treatment Outcome of 18-Month, Day Hospital Mentalization-Based Treatment (MBT) in Patients with Severe Borderline Personality Disorder in the Netherlands

Psychoanalytically oriented day hospital therapy, later manualized and named mentalization-based treatment (MBT), has proven to be a (cost-) effective treatment for patients with severe borderline personality disorder and a high degree of psychiatric comorbidity (BPD) in the United Kingdom (UK). As to yet it has not been shown whether manualized day hospital MBT would yield similar results when conducted by an independent institute outside the UK. We investigated the applicability and treatment outcome of 18-month, manualized day hospital MBT in the Netherlands by means of a prospective cohort study with 45 Dutch patients with severe BPD and a high degree of comorbid Axis I and Axis II disorders. Outcomes were assessed each six months. Symptom distress, social and interpersonal functioning, and personality pathology and functioning all improved significantly, with effect sizes between 0.7 and 1.7. Suicide attempts, acts of self-harm, and care consumption were also significantly reduced. The results indicate that MBT can effectively be implemented in an independent treatment institute outside the UK. This study also supports the clinical effectiveness of manualized day hospital MBT in patients with severe BPD and a high degree of psychiatric comorbidity.     

Distance perception and the ambiguity of visual stimulation: A theoretical note

Certain current views postulate that visual perception, especially of distance, is a function of optical stimulation alone. It is shown here that the optical array does not, in fact, specify absolute distance unambiguously, for either a stationary or a moving O. In view of this ambiguity of optical information, a more complex theory, comprising both visual and nonvisual information, as needed to explain, veridical perception.     

AMOUNT OF INDUCED AVOIDANCE BEHAVIOUR TO LIGHT IN THE PROTOZOA TETRAHYMENA AS A FUNCTION OF TIME AFTER TRAINING AND CELL FISSION

B ergström , S. R. Amount of induced avoidance behaviour to light in the Protozoa Tetrahymena as a function of time after training and cell fission. Scand. J. Psychol ., 1969, 10 , 16–20.—Two cultures of Tetrahymena, dividing synchronously after exposure to an alternating heat treatment, were exposed to series of light and electric shocks paired. After 20 and 30 exposures resp. to the stimulus combination, samples of these cultures were drawn every 18 min and placed in a partially lighted chamber. In samples drawn shortly after training, an essentially smaller proportion was found in the light, in comparison with control samples, which had received either shocks or light or neither of the two stimuli. In later samples, this proportion increased until it approached level of control samples. The course of the increase was not influenced by intervening synchronous cell division.     

AVOIDANCE BEHAVIOUR TO LIGHT IN THE PROTOZOA TETRAHYMENA: The effect of a gradual versus an abrupt boundary between dark and light

B ergström , S. R. Avoidance behaviour to light in the Protozoa Tetrahymena. The effect of a gradual versus an abrupt boundary between dark and light. Scand. J. Psychol ., 1969, 10 , 81–88.—Samples of Tetrahymena, trained to avoid light, were placed in the dark part of a partially lighted chamber. The frequency of animals entering the lighted part through a gradual and through an abrupt boundary between dark and light was observed. It was found that a gradual boundary was a much more effective obstacle to the animals than an abrupt one.     

INDUCED AVOIDANCE BEHAVIOUR IN THE PROTOZOA TETRAHYMENA

B ergstrom , S. R. Induced avoidance behaviour in the Protozoa Tetrahymena. Scand.J. Psychol ., 1968, 9, 215–219.—A sample of Tetrahymena, exposed to a series of light and electric shocks paired, was placed in a partially lighted glass chamber. During the first three minutes the number of animals in the lighted parts of the chamber decreased, and an essentially smaller proportion of the sample was then found in the light, in comparison with control samples, which had received either shocks or light or neither of the two stimuli.     

ACQUISITION OF AN AVOIDANCE REACTION TO LIGHT IN THE PROTOZOA TETRAHYMENA

B ergström , S. R. Acquisition of an avoidance reaction to light in the Protozoa Tetrahymena. Scand. J. Psychol ., 1968, 9 , 220–224.—A culture of Tetra-hymena, dividing synchronously after exposure to an alternating heat treatment, was exposed to a series of light and electric shocks paired. Samples of this culture were drawn after 1, 6, 11, 16, 21, 26, and 31 exposures to the stimulus combination and were then placed in a partially lighted chamber. With an increasing number of stimulus presentations, the proportions of the samples found in the lighted parts decreased, while they remained roughly constant in control samples which had received either shocks or light or neither of the two stimuli.