Color and intensity discrimination in <Emphasis Type="Italic">Xenopus laevis</Emphasis> tadpoles

Investigations into the physiology of Xenopus laevis have the potential to greatly accelerate biomedical research, especially concerning neural plasticity and sensory systems, but are limited by the lack of available information on behavioral learning in this species. Here, we attempt to lay the foundations for a behavioral assay in Xenopus that can be used in conjunction with biological manipulations. We tested cohorts of Xenopus tadpoles across four light-mediated active-avoidance experiments, using either wavelength or intensity as the salient discriminative cue. In the wavelength task, we determine a baseline learning rate and characterize retention of learning, identifying active extinction effects as far more potent than the passage of time in the loss of behavior. In the intensity task, we examine the effects of varying differences between the discriminative stimuli on acquisition and extinction and identify a critical range of intensity differences where learning changes. The results of our experiments demonstrate that Xenopus is a tractable model organism for cognitive research and can learn a variety of associative tasks in the laboratory settings. These data reveal new aspects of the Xenopus larval visual processing system and facilitate future research between cognitive methods and biological/chemical manipulations to study mechanisms of brain structure and function.     

A fertile matrix: the birth of the Forensic Psychotherapy Society

This paper traces some aspects of the fertile matrix within which, over many years, the application of a psychoanalytic perspective to clinical work with the most severely mentally ill, difficult and at times frightening patients in secure and community settings has evolved and now led to the recent inauguration of the Forensic Psychotherapy Society (FPS), a new Member Institution of the British Psychoanalytic Council. The Society provides both a framework for a national, multidisciplinary professional training in psychodynamic forensic psychotherapy and the potential launching pad for an active post-qualification organisation supporting CPD and all other forms of professional development. The particular contributions to the birth of the FPS of the Forensic Psychotherapy Department at West London Mental Health NHS Trust, partly because we know it best but also because it is part of the largest forensic psychiatric service in the United Kingdom, are described.     

Walking through doorways causes forgetting: Event structure or updating disruption?

According to event cognition theory, people segment experience into separate event models. One consequence of this segmentation is that when people transport objects from one location to another, memory is worse than if people move across a large location. In two experiments participants navigated through a virtual environment, and recognition memory was tested in either the presence or the absence of a location shift for objects that were recently interacted with (i.e., just picked up or set down). Of particular concern here is whether this location updating effect is due to (a) differences in retention intervals as a result of the navigation process, (b) a temporary disruption in cognitive processing that may occur as a result of the updating processes, or (c) a need to manage multiple event models, as has been suggested in prior research. Experiment 1 explored whether retention interval is driving this effect by recording travel times from the acquisition of an object and the probe time. The results revealed that travel times were similar, thereby rejecting a retention interval explanation. Experiment 2 explored whether a temporary disruption in processing is producing the effect by introducing a 3-second delay prior to the presentation of a memory probe. The pattern of results was not affected by adding a delay, thereby rejecting a temporary disruption account. These results are interpreted in the context of the event horizon model, which suggests that when there are multiple event models that contain common elements there is interference at retrieval, which compromises performance.     

Common magnitude representation of fractions and decimals is task dependent

Although several studies have compared the representation of fractions and decimals, no study has investigated whether fractions and decimals, as two types of rational numbers, share a common representation of magnitude. The current study aimed to answer the question of whether fractions and decimals share a common representation of magnitude and whether the answer is influenced by task paradigms. We included two different number pairs, which were presented sequentially: fraction–decimal mixed pairs and decimal–fraction mixed pairs in all four experiments. Results showed that when the mixed pairs were very close numerically with the distance 0.1 or 0.3, there was a significant distance effect in the comparison task but not in the matching task. However, when the mixed pairs were further apart numerically with the distance 0.3 or 1.3, the distance effect appeared in the matching task regardless of the specific stimuli. We conclude that magnitudes of fractions and decimals can be represented in a common manner, but how they are represented is dependent on the given task. Fractions and decimals could be translated into a common representation of magnitude in the numerical comparison task. In the numerical matching task, fractions and decimals also shared a common representation. However, both of them were represented coarsely, leading to a weak distance effect. Specifically, fractions and decimals produced a significant distance effect only when the numerical distance was larger.     

Walking through doorways causes forgetting: environmental effects

Previous work has shown a decline in memory for objects carried through a doorway versus across a room. The aim of the current study is to extend this work to understand how variations in perceptual experience during these event shifts influence this finding. First a change in procedure to reduce memory load to a single item was assessed. Next we explored whether performance is influenced by spatial distance versus spatial categories, the ability to perceptually preview the next location, and changes in the colour and texture of the walls. The location updating effect was consistently observed for all manipulations, suggesting that such event transformations have a robust influence on human memory. This suggests that event cognition is driven more by the use of perceptual information to infer or impose a categorical shift from one event to another rather than by the nature of perceptual information available at the time.     

Clinical Exchange: The Architectural Failure

The Clinical Exchange invites eminent clinicians of diverse persuasions to share, in ordinary language, their clinical formulations and treatment plans of the same psychotherapy patient—one not selected or nominated by those therapists—and then to discuss points of convergence and contention in their recommendations. This Exchange concerns a Mr. L, a 47-year-old, married man presenting for outpatient individual psychotherapy with chief complaints of depression, anxiety, and a lengthy history of vocational underachievement. Drs. Herbert Fensterheim, Leslie Greenberg, and Leigh McCullough, who anchor their practices in the cognitive-behavioral, experiential, and psychodynamic orientations, respectively, are the featured commentators. Finally, Dr. Jerold Gold, the case contributor and Mr. L's psychotherapist, provides a few closing comments.