On the detectability of straight lines in visual noise: An extension of French’s paradigm into the millisecond domain

We report the results of a study that investigated the effects of four experimental parameters on the tachistoscopic detectability of dotted lines in a noisy background consisting of dynamic patterns of identical dots. Characteristics of the lines that were explored included dot spacing, dot numerosity, and line orientation. Dot spacing was shown to be the most powerful parameter in determining the masking effect: the closer the dots, the more easily the line was detected. Increasing the number of the dots was also effective in increasing the detectability of a line, but only up to a limit of five dots. The orientation of the line, on the other hand, did not alter its detectability. Increasing the density of the visual masking noise monotonically reduced the detectability of the line. These studies are an extension of French’s (1953, 1954) work, differing mainly in the fact that the stimulus material was presented tachistoscopically rather than in a mode that allowed prolonged (up to 5 sec) examination of the figures. Thus, they put the results in a domain in which physiological interpretations may be more critically evaluated. A comparison of the results suggests that essentially the same sorts of cognitive mechanisms are operating in the millisecond domain as in the longer exposures. This suggests that simple neurological models utilizing the concept of feature filters or detectors may be being prematurely applied to relatively complex perceptual processes.     

CULTURAL DIFFERENCES IN REACTION TO FAILURE1

Les Occidentaux admettent qu'on critique leur performance; ils réagissent en général à la critique en essayant de faire mieux. En Extrême-Orient, il n'est pas convenable de dire à quelqu'un qu'il a échoué en quelque chose; le faisant, on a toute chance de le voir renoncer ou faire plus mal encore. Cette différence de comportement dans les deux civilisations s'explique par des différences d'organisation cognitive. Les AA. ont comparé, dans trois groupes d'étudiants de culture différente (Américains; Extrême-orientaux suivant les cours d'universités américaines; Thais de Thaïlande), les individus qui ont réussi et ceux qui ont échoué dans leurs études. Les sujets américains réagissent à l'échec en réduisant les relations entre toutes les variables étudiées, ce qui constitue un mode de défense en profondeur par le biais d'une organisation plus souple. Les sujets des deux autres groupes réagissent à l'échec par une réduction des contacts personnels et une rigidité accrue de l'organisation personnelle interne. Ces résultats ont une grande importance pratique relativement aux effets sociaux du développement économique en Extrême-Orient.     

Dynamic visuometric techniques

A general technique is described to automate the measurement of visual thresholds. The method is based on the dynamic analog of the method of adjustment, incorporating continuous feedback. Threshold is treated as a system interaction between some level of response and sensed input. The S tracks a stimulus that continually oscillates in magnitude around threshold. The accuracy and variability of the S’s response provides a dynamic and functional assessment of the threshold under the condition of the experiment. Techniques for instrumenting several visuometric procedures are described.     

Tables of event sequences for sequential analyses of data in psychological experiments containing two-class events

Tables of sequences of two-class events are presented for use in programming psychological experiments in which behavior on trial n may be a function of the events of trials n ? 1, n ? 2, and/or n ? 3. Various factors related to schedule generation are discussed, i.e., restrictions on trial-block length which accompany sequential balance, interrelationships of trial blocks in the multiblock experiment, relationships between run length and r-tuple occurrences, and alternation behavior. Following a consideration of various methods of schedule generation for the two-class experiment, it was concluded that no method can result in schedules that possess all properties considered desirable in psychological experiments. However, the present sequences allow for sequential balance and analysis, and thus should prove useful in producing schedules in some contexts that are standard with regard to sequential influences.