An LCD tachistoscope with submillisecond precision

Tachistoscopes allow brief visual stimulation delivery, which is crucial for experiments in which subliminal presentation is required. Up to now, tachistoscopes have had shortcomings with respect to timing accuracy, reliability, and flexibility of use. Here, we present a new and inexpensive two-channel tachistoscope that allows for exposure durations in the submillisecond range with an extremely high timing accuracy. The tachistoscope consists of two standard liquid-crystal display (LCD) monitors of the light-emitting diode (LED) backlight type, a semipermeable mirror, a mounting rack, and an experimental personal computer (PC). The monitors have been modified to provide external access to the LED backlights, which are controlled by the PC via the standard parallel port. Photodiode measurements confirmed reliable operation of the tachistoscope and revealed switching times of 3?μs. Our method may also be of great advantage in single-monitor setups, in which it allows for manipulating the stimulus timing with submillisecond precision in many experimental situations. Where this is not applicable, the monitor can be operated in standard mode by disabling the external backlight control instantaneously.     

Time-based and event-based prospective memory across adulthood: underlying mechanisms and differential costs on the ongoing task

The authors investigated the phenomenon that performance in an ongoing task declines when individuals must carry out a prospective memory (PM) task. This effect is referred to as the PM interference effect. The authors examined whether the PM interference effect differs between event-based and time-based PM tasks and whether it is increased among the elderly. The authors also investigated adult age differences in PM performance and the potential underlying mechanisms of the age deficits in PM. They found that the PM interference effect was greater in event-based than in time-based tasks. However, aging was not associated with an increase in PM interference effects. Age differences in PM performance were more exaggerated in time-based than event-based PM, but they were not mediated by age differences in traditional cognitive ability measures. In time-based PM, age showed a unique adverse effect even after controlling for the ability to externally monitor the time, leading to the possibility that aging disrupts time-based PM because of deficits in internally processing the time.     

Sex differences in retention of verbal and spatial characteristics of stimuli: A cross-cultural replication

This study is a partial (omitting college students) replication of R. V. Kail and A. W. Siegel (Journal of Experimental Child Psychology, 1977, 23, 341–347) in Ghana and Scotland on boys and girls with 4 and 7 years of education. After viewing sets of five or seven letters in a 4 × 4 matrix they remembered either (a) the letters, (b) positions of the letters, or (c) both letters and positions. Contrary to the results of the original study, no sex difference in relative recall of letters and positions was found. There was also evidence that verbal and spatial information is not always processed independently. A prediction that Scottish children would have better recall of positions was supported. The discussion notes the limitations of intracultural research as a basis for generalizations.     

Ethnic identity and preferences among Asian immigrant children in Glasgow: A replicated study

The aim of first study, carried out by an English investigator, was to assess the extent to which Asian immigrant children had moved away from the values of their culture of origin. For this purpose some novel techniques were employed, including an identikit task and one focusing on Scottish versus Asian names. The outcome suggested that the children had been very powerfully influenced by the values of the host community. Since it was suspected that these results might have been in part a function of the ethnic membership of the investigator and/or the specific methods employed, the study was repeated on a comparable sample with an Indian psychologist and using modified test materials. The results of the second study remained unchanged as far as factual aspects were concerned; however, preferences expressed changed significantly in the direction of Asian cultural values. The theoretical and methodological implications of these findings are discussed, and it is argued that studies of this type are likely to have an inherent element of uncertainty which calls for caution in making generalizations.     

Recognition vs recall of visually vs acoustically confusable letter matrices

In an attempt to separate auditory and visual components in short-term memory, five subjects were exposed to letter matrices composed of six visually confusable letters, six acoustically confusable letters, or a mixture of the two, under two response conditions: recognition and recall. A 50-msec stimulus presentation was followed by a variable dark interval of 1, 250, 1,000, or 3,000 msec. In the recall condition, the interval was followed by a buzzer which signaled the subject to recall, in any order, as many letters as possible. In the recognition condition, the variable interval was followed by a second letter matrix which was either identical to the first matrix or differed from is by one letter. Subjects responded either "same" or "different." The results support the notion that the auditory component plays a major role in recall, whereas the visual component dominates in recognition.     

SCALES FOR SUBJECTIVE DISTANCE

By means of the method of ratio estimation, scale values were obtained for subjective distance. In three experiments different stimulus ranges of the objective distances were used. It was found: ( 1 ) Subjective distance is a power function of the objective distance. ( 2 ) The exponent of the function varies with the stimulus range. With increasing stimulus range the exponent has a tendency to decrease. It is conceivable that the change of the exponent may be explained by an adaptation of the subjective range to the stimulus range.     

LSD response in Eysenckian trait types identified by polypredictive CFA

The four personality type combinations derived from high and low extraversion () and high and low neuroticism () have been related to response patterns composed of three symptoms (affective disturbances, thinking disturbances, and blackouts) scored as present (+) or absent (−) after a single oral dose of the hallucinogenic drug LSD-25. Hypotheses for expected response patterns for each personality group were derived from a data set obtained by Kohnen and Lienert (1987). Significance of associations was tested by two strategies of polyprediction configural frequency analysis (CFA): multiple uniprediction and biprediction CFA. Both strategies yielded a significant hyperpresentation of all three symptoms present in E+N+ (hysterics), merely thinking disorders in dysthymics (E−N+), merely affective symptoms in E+N− (stable extraverts), and merely blackouts in N−E− (stable introverts). Authors tried to relate these symptoms to Kretschmer's temperament types and could afterwards show by a chessboard modification of prediction CFA, that by applying two combined hypotheses for two personality types each, the significance of the predicted associations could be increased.     

MEASUREMENT OF THE INTENSITY OF AN UNDERLYING FIGURAL PROCESS: A methodological study

K ünnapas , T. M. Measurement of the intensity of an underlying figural process. A methodological study. Scand. J. Psychol ., 1961, 2 , 174–184.—A method is proposed for studying the intensity of the figural process underlying the well-known phenomenon of figural fluctuations. A metric model is presented according to which a measure of the intensity of the underlying process is obtained in units of dispersion. The model is illustrated by an experimental example. An equation is given which is analogous to that of the damped harmonic vibration. Four parameters are involved in this equation. A technique for determining the parameters is developed. Very good agreement between theoretical and empirical scale values demonstrates the applicability of the proposed method.