Stroop-like interference in chess players' imagery: An unexplored possibility to be revealed by the adapted moving-spot task

Summary A group of highly skilled chess players and two control groups of subjects (nonskilled players and nonplayers) participated in a moving-spot task (cf. Attneave & Curlee, 1983). They had to move either a spot or one of several chess pieces within an imaginary grid according to instructions given by the experimenter (the imaginary motion of the imaginary object consisted of a quasirandom sequence of steps in the direction — up, right, left, or down). The general findings were as follows: (1) chess players' error rates were lower than those in the nonplayer group; (2) in a moving-spot condition there were no significant differences in the efficiency of skilled vs. nonskilled player groups; (3) in a moving chess-piece condition, ranges of spatial errors differed for chess-player and nonplayer groups, depending on the symbolic meaning of the chess pieces in the former group; (4) in a moving chess-piece condition we also found tendencies for Stroop-like interference in the group of skilled players (e. g., bishop moving illegally up, right, etc.); (5) all groups benefitted from the use of a checkerboard instead of an 8 × 8 grid as the imaginary spatial framework within which to move a piece; (6) thepost hoc analysis showed that the two small selected subgroups of subjects comprising those who used either pure visual strategy or pure chess-annotation strategy were susceptible to some Stroop-like interference and that the set of pieces with the highest incongruity of moves (bishop, knight) yielded higher error rates than the set of pieces that had congruity of moves (king, rook). Taken together, these results seem to indicate that visuospatial tasks like Attneave and Curlee's (1983) moving-spot task are performed neither on the basis of a static picture-in-the-head type of visual image, for which it is just the same whether one or another type of piece is imaginarily moved, nor on the basis of purely symbolic or propositional operations that bear no relation to the visual-configurational and spatial-localizational representations. Imagery seems to constitute a dynamicprocess of interplay between visuospatial and verbal-propositional codes.     

Experiences at a neurologico-psychiatric department in Ethiopia

On three separate occasions, the authors taught at Gondar School of Medicine, attached to the University of Addis Ababa. They found that the neurological group of patients was determined by geographical rather than specifically tropical conditions, and that the psychiatric syndromes resembled those here, considerably influenced, however, by traditional rural medicine. The paper makes observations on comparative psychopathology.     

Reviews of current books

Pastoral Psychology -     

Perceptual acceleration of objects in stream: evidence from flash-lag displays

An object in continuous motion is perceived ahead of the briefly flashed object, although the two images are physically aligned (Nijhawan, 1994), the phenomenon called flash-lag effect. Flash-lag effects have been found also with other continuously changing features such as color, pattern entropy, and brightness (Sheth, Nijhawan, & Shimojo, 2000) as well as with streamed pre- and post-target input without any change of the feature values of streaming items in feature space (Bachmann & P?der, 2001a. 2001b). We interpret all instances of the flash-lag as a consequence of a more fundamental property of conscious perception in general: acceleration of the speed with which samples of perceptual information become represented in explicit format immediately after the stimulation onset. Decreased visual latency of the samples of stimulus information from the streamed input leads to the relative perceptual lag for the separately flashed stimulus because it is not preceded by adjacent sensory input that would have accelerated its perception. Experimental support for the notion of perceptual acceleration is reviewed.     

Detection, genetic counseling and phenotype prevention of Duchenne muscular dystrophy

Literature data and the own ascertainment of Duchenne muscular dystrophy cases concentrated on the Leipzig county confirm the necessity of early diagnosis and of central registration, search for female carries and genetic counselling. A newborn screening is supported provided that its organization will be practicable. About 12% of Duchenne cases are secondary affections of brothers. It should be possible to prevent one third of all cases by means of counselling also of the female relatives of the mothers. The repeated estimation of serum creatinkinase activity, completed by electromyography, has the greatest practical importance for the identification of heterozygous carriers. For the genetic counselling of definite carriers and women at risk it is possible only to recommend intrauterine sex prediction and the selective abortion of male fetuses.     

Flash-lag effect: complicating motion extrapolation of the moving reference-stimulus paradoxically augments the effect

One fundamental property of the perceptual and cognitive systems is their capacity for prediction in the dynamic environment; the flash-lag effect has been considered as a particularly suggestive example of this capacity (Nijhawan in nature 370:256-257, 1994, Behav brain sci 31:179-239, 2008). Thus, because of involvement of the mechanisms of extrapolation and visual prediction, the moving object is perceived ahead of the simultaneously flashed static object objectively aligned with the moving one. In the present study we introduce a new method and report experimental results inconsistent with at least some versions of the prediction/extrapolation theory. We show that a stimulus moving in the opposite direction to the reference stimulus by approaching it before the flash does not diminish the flash-lag effect, but rather augments it. In addition, alternative theories (in)capable of explaining this paradoxical result are discussed.     

Individual differences in metacontrast: An impetus for clearly specified new research objectives in studying masking and perceptual awareness?

While the majority of perceptual phenomena based research on consciousness is implicitly nomothetic, some idiographic perspective can be sometimes highly valuable for it. It may turn out that after having had a closer look at individual differences in the expression of psychometric functions a need to revise some nomothetic laws considered as the general ones arises as well. A study of individual differences in metacontrast masking published in this issue superbly illustrates this. A myriad of urgent research objectives emerges out of this study, most of them important both for clearing up the still messy theoretical picture on visual masking and for the beginning of asking whether perceptual awareness mechanisms are so universal at all. In this commentary the problems pertinent to this issue are discussed.     

Precuing an isolated stimulus temporarily outweighs in-stream stimulus facilitation

The flash-lag effect (FLE), when studied in rapid serial visual presentations, has shown that participants perceived a target presented in a stream prior to its simultaneous out-of-stream replica (T. Bachmann & E. P?der, 2001). In the present study, the authors introduced a precue to the single flashed, isolated target to see if drawing bottom-up attention to the flash also would compensate for the effects of the mechanisms that influence the processing of in-stream items. The extent of the flash-lead effect in the precued condition was considerably larger than the lead-effect in earlier experiments and in a control experiment where no precue was presented for the flashed targets. For the first 200-250 ms from the beginning of the stream, flash-lead dominated. The FLE did not appear until 400 ms after stream onset. The authors interpret results as the combined relative effects of in-stream target masking, in-stream sensory facilitation, and spatial-attentional facilitation.