The impact of September 11 on dreaming

This study focuses on a set of dreams related to the September 11, 2001 terrorist attacks and their aftermath, using content analysis and cognitive psychology to explore the interweaving of external public catastrophe and internal psychological processes. The study tests several recent claims in contemporary dream research, including the central image theory of Hartmann [Hartmann, E., & Basile, R. (2003). Dream imagery becomes more intense after 9/11/01. Dreaming, 13(2), 61-66; Hartmann, E., & Brezler, T. (2008). A systematic change in dreams after 9/11/01. Sleep, 31(2), 213-218], the media exposure factor postulated by Propper [Propper, R. E., Stickgold, R., Keeley, R., & Christman, S. D. (2007). Is television traumatic? Dreams, stress, and media exposure in the aftermath of September 11, 2001. Psychological Science, 18(4), 334-340], the continuity hypothesis of Domhoff [Domhoff, W. G. (1996). Finding meaning in dreams: A quantitative approach. New York: Plenum], the cognitive and metacognitive approach of Kahan [Kahan, T. L. (2001). Consciousness in dreaming: A metacognitive approach. In K. Bulkeley (Ed.), Dreams: A reader on the religious, cultural, and psychological dimensions of dreaming (pp. 333-360). New York: Palgrave], and the threat simulation theory of Revonsuo [Revonsuo, A. (2000). The reinterpretation of dreams: An evolutionary hypothesis of the function of dreaming. Behavioral and Brain Sciences, 23(6), 877-901]. Our findings suggest the terrorist attacks had a tangible impact on the content of many people's dreams, but did not fundamentally alter the cognitive processing features of their dreaming. The 9/11 attacks affected what they dreamed about, but not the way they dreamed.     

Ontology in Cognitive Perspective

Ontology cannot be left to the natural sciences, if only because it deals also with hypothetical and fictional objects. It pivots about proto-categorical issues relating to the features of objects of any and all kinds. This brings into its range issues that test the limits of knowledge by asking questions that are inherently unanswerable (for example: “What is an instance of an occurrence that no one ever mentions?”). And it raises issues of norms and values that science (in its usual configuration) does not address.     

Do infants possess an evolved spider-detection mechanism?

Previous studies with various non-human animals have revealed that they possess an evolved predator recognition mechanism that specifies the appearance of recurring threats. We used the preferential looking and habituation paradigms in three experiments to investigate whether 5-month-old human infants have a perceptual template for spiders that generalizes to real-world images of spiders. A fourth experiment assessed whether 5-month-olds have a perceptual template for a non-threatening biological stimulus (i.e., a flower). The results supported the hypothesis that humans, like other species, may possess a cognitive mechanism for detecting specific animals that were potentially harmful throughout evolutionary history.     

Working memory involved in predicting future outcomes based on past experiences

Deficits in working memory have been shown to contribute to poor performance on the Iowa Gambling Task [IGT: Bechara, A., &; Martin, E.M. (2004). Impaired decision making related to working memory deficits in individuals with substance addictions. Neuropsychology, 18, 152–162]. Similarly, a secondary memory load task has been shown to impair task performance [Hinson, J., Jameson, T. &; Whitney, P. (2002). Somatic markers, working memory, and decision making. Cognitive, Affective, &; Behavioural Neuroscience, 2, 341–353]. In the present study, we investigate whether the latter findings were due to increased random responding [Franco-Watkins, A. M., Pashler, H., &; Rickard, T. C. (2006). Does working memory load lead to greater impulsivity? Commentary on Hinson, Jameson, and Whitney’s (2003). Journal of Experimental Psychology: Learning, Memory &; Cognition, 32, 443–447]. Participants were tested under Low Working Memory (LWM; n = 18) or High Working Memory (HWM; n = 17) conditions while performing the Reversed IGT in which punishment was immediate and reward delayed [Bechara, A., Dolan, S., &; Hindes, A. (2002). Decision making and addiction (part II): Myopia for the future or hypersensitivity to reward? Neuropsychologia, 40, 1690–1705]. In support of a role for working memory in emotional decision making, compared to the LWM condition, participants in the HWM condition made significantly greater number of disadvantageous selections than that predicted by chance. Performance by the HWM group could not be fully explained by random responding.     

Microstructural integrity of the corpus callosum linked with neuropsychological performance in adolescents

Background: Diffusion tensor imaging (DTI) has revealed microstructural aspects of adolescent brain development, the cognitive correlates of which remain relatively uncharacterized. Methods: DTI was used to assess white matter microstructure in 18 typically developing adolescents (ages 16–18). Fractional anisotropy (FA) and mean diffusion (MD) were evaluated within the splenium and body of the corpus callosum in relation to cognitive performance. Results: Visuospatial construction abilities were associated with white matter integrity in both the splenium and body of the corpus callosum, while only splenium integrity was associated with language and psychomotor function. Conclusion: Results suggest that, for typically developing adolescents, white matter coherence positively relates to visuospatial, psychomotor, and language skills. These findings may have implications for the cognitive functioning of clinical populations in which typical white matter development is altered.     

The relationship between the shape of the mental number line and familiarity with numbers in 5- to 9-year old children: evidence for a segmented linear model

This experiment aimed to expand previous findings on the development of mental number representation. We tested the hypothesis that children's familiarity with numbers is directly reflected by the shape of their mental number line. This mental number line was expected to be linear as long as numbers lay within the range of numbers children were familiar with. Five- to 9-year-olds (N=78) estimated the positions of numbers on an external number line and additionally completed a counting assessment mirroring their familiarity with numbers. A segmented regression model consisting of two linear segments described number line estimations significantly better than a logarithmic or a simple linear model. Moreover, the change point between the two linear segments, indicating a change of discriminability between numbers, was significantly correlated with children's familiar number range. Findings are discussed in terms of the accumulator model, assuming a linear mental representation with scalar variability.     

Discerning the Division of Cognitive Labor: An Emerging Understanding of How Knowledge Is Clustered in Other Minds

The division of cognitive labor is fundamental to all cultures. Adults have a strong sense of how knowledge is clustered in the world around them and use that sense to access additional information, defer to relevant experts, and ground their own incomplete understandings. One prominent way of clustering knowledge is by disciplines similar to those that comprise the natural and social sciences. Seven studies explored an emerging sense of these discipline-based ways of clustering of knowledge. Even 5-year-olds could cluster knowledge in a manner roughly corresponding to the departments of natural and social sciences in a university, doing so without any explicit awareness of those academic disciplines. But this awareness is fragile early on and competes with other ways of clustering knowledge. Over the next few years, children come to see discipline-based clusters as having a privileged status, one that may be linked to increasingly sophisticated assumptions about essences for natural kinds. Possible mechanisms for this developmental shift are examined.     

Flexibility of cue use in the fox squirrel (Sciurus niger)

Recent work on captive flying squirrels has demonstrated a novel degree of flexibility in the use of different orientation cues. In the present study, we examine to what extent this flexibility is present in a free-ranging population of another tree squirrel species, the fox squirrel. We trained squirrels to a rewarded location within a square array of four feeders and then tested them on transformations of the array that either pitted two cue types against one cue type, the majority tests, or all cue types against each other, the forced-hierarchy test. In Experiment 1, squirrels reoriented to the two-cue-type location in all majority tests and to the location indicated by the visual features of the feeders in the forced-hierarchy test. This preference for visual features runs contrary to previous studies that report the use of spatial cues over visual features in food-storing species. In Experiments 2-5 we tested squirrels with different trial orders (Experiments 2 and 3), a different apparatus (Experiment 4) and at different times of the year (Experiment 5) to determine why these squirrels had chosen to orient using visual features in the first experiment. Like captive flying squirrels, free-ranging fox squirrels showed a large degree of flexibility in their use of cues. Furthermore, their cue use appeared to be sensitive both to changes in the test apparatus and the season in which we tested. Altogether our results suggest that the study of free-ranging animals over a variety of conditions is necessary for understanding spatial cognition.     

Sign- and goal-tracking in Atlantic cod (<Emphasis Type="Italic">Gadus morhua</Emphasis>)

When animals associate a stimulus with food, they may either direct their response towards the stimulus (sign-tracking) or towards the food (goal-tracking). The direction of the conditioned response of cod was investigated to elucidate how cod read cue signals. Groups of cod were conditioned to associate a blinking light (conditioned stimulus, CS) with a food reward (unconditioned stimulus, US), with the CS and the US located at opposite sides of the tank. Two groups were trained in a delay conditioning procedure (CS = 60 s, interstimulus interval = 30 s) and two groups were trained in a trace conditioning procedure (CS = 12 s, trace interval = 20 s). The response pattern was similar for the delay- and trace-conditioned groups. The initial main response at the onset of the CS was approaching the blinking lights, i.e. sign-tracking. In the early trials, the fish did not gather in the feeding area before the arrival of food. In the later trials, the fish first approached the blinking lights, but then moved across the tank and gathered below the feeder before the food arrived, i.e. sign-tracking followed by goal-tracking within each trial. These two responses are interpreted as reflecting two learning systems, i.e. one rapid, reflexive response directed at the signal (sign-tracking) and one slower, more flexible response based on expectations about time and place for arrival of the food (goal-tracking). The ecological significance of these two learning systems in cod is discussed.     

The frozen cyborg: A reply to Selinger and Engström

Selinger and Engstrom, A moratorium on cyborgs: Computation, cognition and commerce, 2008 (this issue) urge upon us a moratorium on ‘cyborg discourse’. But the argument underestimates the richness and complexity of our ongoing communal explorations. It leans on a somewhat outdated version of the machine metaphor (exemplified perhaps by a frozen 1970’s Cyborg). The modern cyborg, informed by an evolving computational model of mind, can play a positive role in the critical discussions that Selinger and Engstrom seek.