Three turtles in danger: spontaneous construction of causally relevant spatial situation models

In 4 experiments, the author explored the spontaneous construction of spatial situation models during discourse comprehension by using the sentence-recognition paradigm of J. D. Bransford, J. R. Barclay, and J. J. Franks (1972). In Experiment 1, signaling causal relevance of spatial relations was a necessary precondition for replicating their original finding of spontaneously constructed spatial representations. Causal relevance was ensured in the subsequent experiments by a judgment task indirectly demanding the evaluation of described spatial relations with regard to causal relevance. Participants spontaneously constructed spatial situation models of text presented auditorily or visually. Effects of spontaneous construction were more reliable when encoding was easier. The results suggest a revised interpretation of J. D. Bransford et al.'s study and corroborate recent evidence showing that relevant spatial information in texts is reliably represented.     

How positive affect modulates cognitive control: reduced perseveration at the cost of increased distractibility

A fundamental problem that organisms face in a changing environment is how to regulate dynamically the balance between stable maintenance and flexible switching of goals and cognitive sets. The authors show that positive affect plays an important role in the regulation of this stability-flexibility balance. In a cognitive set-switching paradigm, the induction of mild increases in positive affect, as compared with neutral or negative affect, promoted cognitive flexibility and reduced perseveration, but also incurred a cost in terms of increased distractibility. Rather than influencing set switching in an unspecific way, positive affect thus exerted opposite effects on perseveration and distractibility. Results are consistent with neuropsychological models according to which effects of positive affect on cognitive control are mediated by increased dopamine levels in frontal brain areas.     

The nature of the mental representation of radicals in Chinese: a priming study

Using a priming procedure, 4 experiments were carried out to investigate the effects of a short preexposure of a prime that was a radical or contained radicals identical to the target. Significant facilitation was found when the target contained the prime as a radical, although only for low-frequency targets which did not arise merely as a result of graphical similarity. Facilitation also occurred when the prime and target shared a radical in the same position but not when in different positions. When the prime and target had exactly the same radicals but in different positions, however, the priming effect was inhibitory. This set of results suggests that simple characters (radicals) and complex characters are represented at a different level.     

Modeling the effects of prior knowledge on learning incongruent features of category members

The authors conducted 3 experiments addressing the issue of how observations and multiple sources of prior knowledge are put together in category learning. In Experiments 1 and 2, learning was faster for critical features, which were predictable on the basis of prior knowledge, than for filler features, and this advantage increased as more observations were made. In addition, learning was fastest for incongruent features that could only be predicted using knowledge from other domains. In Experiment 3, presenting contradictory features that violated prior knowledge led to rote learning rather than use of prior knowledge. The results were simulated with the Baywatch model, which addresses how observations of category members lead to recruitment and selection of sources of prior knowledge.     

Cue-focused and reflexive-associative processes in prospective memory retrieval

Several theories of event-based prospective memory were evaluated in 3 experiments. The results depended on the association between the target event and the intended action. For associated target-action pairs (a) preexposure of nontargets did not reduce prospective memory, (b) divided attention did not reduce prospective memory, (c) prospective memory was better than when the target event and intended action were not associated, and (d) prospective memory was characterized by retrieval of the precise intended action. These results converge on the view that retrieval is mediated by a reflexive-associative process. In contrast, for unassociated pairs (a) preexposure of nontargets reduced prospective memory, and (b) divided attention reduced prospective memory. These results implicate cue-focused retrieval processes and are most consistent with a discrepancy-plus-search model. The entire pattern implicates both cue-focused and reflexive-associative processes and more generally supports a multiprocess framework of prospective memory (M. A. McDaniel & G. O. Einstein, 2000).     

ERP study of pre-attentive auditory processing in treatment-refractory schizophrenia

Event-related potential (ERP) studies have demonstrated impaired auditory sensory processing in patients with schizophrenia, as reflected in abnormal mismatch negativity (MMN). We sought to extend this finding by evaluating MMN in 13 treatment-refractory patients with schizophrenia, and 14 age- and gender-matched healthy controls. Subjects responded to infrequent visual stimulation while ignoring binaurally presented auditory tones. The amplitude and topographical pattern of the MMN were analyzed. The control group presented the expected reduction in the amplitude of the MMN from frontal to central and parietal locations. In comparison, the MMN amplitude was not reduced in the treatment-refractory patients, and was largest at the central-posterior electrode location. In addition, patients displayed larger negativities at left frontal, and left- and right-temporal electrode locations than the control subjects. These findings are consistent with pre-attentive abnormalities in treatment-refractory patients with schizophrenia.     

Impaired pitch production and preserved rhythm production in a right brain-damaged patient with amusia

Pre- and postmorbid singing of a patient with amusia due to a right-hemispheric infarction was analyzed acoustically. This particular patient had a premorbid tape recording of her own singing without accompaniment. Appropriateness of pitch interval and rhythm was evaluated based on ratios of pitch and duration between neighboring notes. The results showed that melodic contours and rhythm were preserved but individual pitch intervals were conspicuously distorted. Our results support a hypothesis that pitch and rhythm are subserved by independent neural subsystems. We concluded that action-related acoustic information for controlling pitch intervals is stored in the right hemisphere.     

Hemispheric differences in the recognition of partly occluded objects by newly hatched domestic chicks (<Emphasis Type="Italic">Gallus gallus</Emphasis>)

Domestic chicks are capable of perceiving as a whole objects partly concealed by occluders (amodal completion). In previous studies chicks were imprinted on a certain configuration and at test they were required to choose between two alternative versions of it. Using the same paradigm we now investigated the presence of hemispheric differences in amodal completion by testing newborn chicks with one eye temporarily patched. Separate groups of newly hatched chicks were imprinted binocularly: (1) on a square partly occluded by a superimposed bar, (2) on a whole or (3) on an amputated version of the square. At test, in monocular conditions, each chick was presented with a free choice between a complete and an amputated square. In the crucial condition 1, chicks tested with only their left eye in use chose the complete square (like binocular chicks would do); right-eyed chicks, in contrast, tended to choose the amputated square. Similar results were obtained in another group of chicks imprinted binocularly onto a cross (either occluded or amputated in its central part) and required to choose between a complete or an amputated cross. Left-eyed and binocular chicks chose the complete cross, whereas right-eyed chicks did not choose the amputated cross significantly more often. These findings suggest that neural structures fed by the left eye (mainly located in the right hemisphere) are, in the chick, more inclined to a global analysis of visual scenes, whereas those fed by the right eye seem to be more inclined to a featural analysis of visual scenes.     

Selection of tool diameter by New Caledonian crows<Emphasis Type="Italic"> Corvus moneduloides</Emphasis>

One important element of complex and flexible tool use, particularly where tool manufacture is involved, is the ability to select or manufacture appropriate tools anticipating the needs of any given task—an ability that has been rarely tested in non-primates. We examine aspects of this ability in New Caledonian crows—a species known to be extraordinary tool users and manufacturers. In a 2002 study, Chappell and Kacelnik showed that these crows were able to select a tool of the appropriate length for a task among a set of different lengths, and in 2002, Weir, Chappell and Kacelnik showed that New Caledonian crows were able to shape unfamiliar materials to create a usable tool for a specific task. Here we examine their handling of tool diameter. In experiment 1, we show that when facing three loose sticks that were usable as tools, they preferred the thinnest one. When the three sticks were presented so that one was loose and the other two in a bundle, they only disassembled the bundle when their preferred tool was tied. In experiment 2, we show that they manufacture, and modify during use, a tool of a suitable diameter from a tree branch, according to the diameter of the hole through which the tool will have to be inserted. These results add to the developing picture of New Caledonian crows as sophisticated tool users and manufacturers, having an advanced level of folk physics.Electronic Supplementary Material Supplementary material is available in the online version of this article at