Opportunistic use of cognitive smokescreens by araneophagic jumping spiders

Little is known about how a prey species' cognitive limitations might shape a predator's prey-capture strategy. A specific hypothesis is investigated: predators take advantage of times when the prey's attention is focussed on its own prey. Portia fimbriata, an araneophagic jumping spider (Salticidae) from Queensland, is shown in a series of 11 experiments to exploit opportunistically a situation in which a web-building spider on which it preys, Zosis genicularis (Uloboridae), is preoccupied with wrapping up its own prey. Experimental evidence supports three conclusions: (1) while relying on optical cues alone, P. fimbriata perceives when Z. genicularis is wrapping up prey; (2) when busy wrapping up prey, the responsiveness of Z. genicularis to cues from potential predators is diminished; and (3) P. fimbriata moves primarily during intervals when Z. genicularis is busy wrapping up prey. P. fimbriata's strategy is effective partly because the wrapping behaviour of Z. genicularis masks the web signals generated by the advancing P. fimbriata's footsteps and also because, while wrapping, Z. genicularis' attention is diverted away from predator-revealing cues. Electronic Publication     

Dual processes in recognition: Does a focus on measurement operations provide a sufficient foundation?

Current theoretical thinking about dual processes in recognition relies heavily on the measurement operations embodied within the process dissociation procedure. We critically evaluate the ability of this procedure to support this theoretical enterprise. We show that there are alternative processes that would produce a rough invariance in familiarity (a key prediction of the dual-processing approach) and that the process dissociation procedure does not have the power to differentiate between these alternative possibilities. We also show that attempts to relate parameters estimated by the process dissociation procedure to subjective reports (remember-know judgments) cannot differentiate between alternative dual-processing models and that there are problems with some of the historical evidence and with obtaining converging evidence. Our conclusion is that more specific theories incorporating ideas about representation and process are required.     

The Role of Families and Care Givers as Risk and Protective Factors in Preventing Youth Violence

This paper reviews research which discusses the risk and protective functions that families and other caregivers provide in influencing the development of aggressive behavior in youth. Currently, there is an emphasis on providing violence prevention programs in the school environment, typically with little parental or caregiver involvement. By enhancing the role of families and caregivers in youth violence prevention programs, we assert that an unique opportunity exists to both address specific risk factors for violence while enhancing the protective features of the family. Relatedly, the risk literature on youth violence indicates that the most influential risk factors (i.e., the family, community, and peers) have their principle impact on youth aggression outside the school. We suggest a shift in the focus of violence prevention programming that is more inclusive of families as both a risk and protective agent. In support of this position, relevant theory and reviews of exemplary family-involved programs are offered. Challenges to involving youth caregivers are identified and recommendations for overcoming those challenges suggested. Last, recommendations for future research and public policy in the prevention of youth violence are offered.     

Postural stability and hand preference as constraints on one-handed catching performance in children

Effects of postural state and hand preference as constraints on 1-handed catching performance were investigated in different ability groups of children aged 9-10 years. On the basis of pretest data, the authors classified 48 participants into groups of good, intermediate, and poor catchers (n = 16 in each) and asked them to perform 1-handed catches with their preferred and nonpreferred hands while standing and sitting. The good catchers' performance was not affected by the imposed postural constraints but did improve when they used the preferred hand. A similar effect of hand preference was evident in the intermediate and poor catchers, but there was also an effect of postural constraint. Independent of hand preference, intermediate catchers' performance while seated improved significantly compared with that during standing. For poor catchers, there was an interaction between hand preference and posture; significant improvement was evident only when they used the preferred hand in the sitting condition. The finding that manipulation of posture and hand preference affected performance outcomes indicates that perceptual skill is not the only influence on catching performance in children. Manipulation of those key constraints may facilitate the acquisition of catching skill, but more research is needed to determine the permanence of those effects.     

Suppositions, extensionality, and conditionals: a critique of the mental model theory of Johnson-Laird And Byrne (2002)

P. N. Johnson-Laird and R. M. J. Byrne proposed an influential theory of conditionals in which mental models represent logical possibilities and inferences are drawn from the extensions of possibilities that are used to represent conditionals. In this article, the authors argue that the extensional semantics underlying this theory is equivalent to that of the material, truth-functional conditional, at least for what they term "basic" conditionals, concerning arbitrary problem content. On the basis of both logical argument and psychological evidence, the authors propose that this approach is fundamentally mistaken and that conditionals must be viewed within a suppositional theory based on what philosophical logicians call the Ramsey test. The Johnson-Laird and Byrne theory is critically examined with respect to its account of basic conditionals, nonbasic conditionals, and counterfactuals.     

Does selective attention influence the octave illusion?

The octave illusion occurs when each ear receives a sequence of tones alternating by one octave, but with different frequencies in each ear. Most listeners report a high pitch in one ear alternating with a low pitch in the opposite ear. Deutsch and Roll proposed an influential suppression model of the illusion in which the pitch is determined by ear dominance, while the location of this pitch is determined by high-frequency dominance. Deutsch later suggested that this unusual division between 'what' and 'where' mechanisms is facilitated by sequential interactions within the eliciting sequence. A recent study has raised doubts about the suppression model and the role of sequential interactions in the illusion (Chambers et al, 2002 Journal of Experimental Psychology: Human Perception and Performance 28 1288-1302). Here, we examined whether this previous null effect of sequential interactions may have arisen because of uncontrolled influences of selective attention. The results reveal no evidence of a link between selective attention and sequential interactions, thus consolidating doubts about the validity of the suppression model.     

Human cognition and a pile of sand: a discussion on serial correlations and self-organized criticality

Recently, G. C. Van Orden, J. G. Holden, and M. T. Turvey (2003) proposed to abandon the conventional framework of cognitive psychology in favor of the framework of nonlinear dynamical systems theory. Van Orden et al. presented evidence that "purposive behavior originates in self-organized criticality" (p. 333). Here, the authors show that Van Orden et al.'s analyses do not test their hypotheses. Further, the authors argue that a confirmation of Van Orden et al.'s hypotheses would not have constituted firm evidence in support of their framework. Finally, the absence of a specific model for how self-organized criticality produces the observed behavior makes it very difficult to derive testable predictions. The authors conclude that the proposed paradigm shift is presently unwarranted.     

The influence of parafoveal word length and contextual constraint on fixation durations and word skipping in reading

The present study examined the relationship between the predictability of words within a sentence and the availability of parafoveal word length information, on when and where the eyes move in reading. Predictability influenced first-pass reading times when parafoveal word length preview information was correct, but not when it was incorrect. Similarly, for saccades launched from near the target word (wordn), predictability influenced the probability with which it was skipped only when the word length preview was correct. By contrast, for saccades launched farther away from wordn, predictability influenced word skipping regardless of the parafoveal word length preview. Taken together, the data suggest that parafoveal word length preview and predictability can act as a joint constraint on the decision of when and where to move the eyes.