A laboratory in experimental psychology using the TRS-80

Twenty-three BASIC language programs have been written to allow the TRS-80 and other microcomputers to perform most of the classical experiments normally used in teaching a laboratory course in experimental psychology. Most programs allow experiments to be run as though the computer was the specialized apparatus normally used. This facilitates a realistic and interactive learning experience for the students.     

Universal one- and two-component interfacing techniques

Many psychologists avoid using microcomputers in teaching and research laboratories because they lack the experience and knowledge necessary for interfacing. A $1 electronic component can connect external circuits into any computer. For output interfacing, circuits are available to control external devices with one or no additional components.     

Identity and sociocultural change: Comparing young indigenous people in Chiapas who have different sociodemographic trajectories

One of the most commonly used distinctions in cross‐cultural studies is the one between individualism and collectivism. One of the criticisms levelled at this distinction is that it fails to incorporate the differences that may exist when comparing people from a rural context with little formal education to people from the same group who live in an urban context where formal education is the norm. Bearing in mind these sociodemographic factors, we have compared the self‐concepts among 104 young indigenous people in Chiapas (Mexico), having divided them into three groups: “rural‐traditional,” “rural–urban” and “urban.” These people's self‐concepts were analysed using a task that contrasts personal self‐concept with social self‐concept and a technique in which participants draw themselves along with the things and people they consider most important to them. The results reveal significant differences between the three groups. The personal categories are given a higher value in the “urban” group while the social categories score higher in the “rural‐traditional” group. Regarding the results of the indigenous self‐portraits, from the content analysis of the drawings, 16 categories emerged. These findings are discussed in the light of Greenfield's theory of social change and human development.     

Near-Death Experiences in a Multi-religious Hospital Population in Sri Lanka

Near-death experiences (NDEs) are a wide range of experiences that occur in association with impending death. There are no published studies on NDEs in general hospital populations, and studies have been mainly conducted on critically ill patients. We assessed the prevalence of NDEs and its associations in a multi-religious population in a general hospital in Sri Lanka. A randomised sample of patients admitted to the Colombo North Teaching Hospital was assessed using the Greyson NDE scale and clinical assessment. Out of total 826 participants, NDEs were described by 3%. Compared to the NDE-negative participants, the NDE-positive group had a significantly higher mean for age and a ratio of men. Women reported deeper NDEs. Patients of theistic religions (Christianity, Islam and Hinduism) reported significantly more NDEs compared to patients from the non-theistic religious group (Buddhism). NDE-positive patient group had significantly higher reporting of a feeling ‘that they are about to die’, the presence of loss of consciousness and a higher percentage of internal medical patients. This is the first time that NDEs are assessed in a general hospital population and NDEs being reported from Sri Lanka. We also note for the first time that persons with theistic religious beliefs reported more NDEs than those with non-theistic religious beliefs. Medical professionals need to be aware of these phenomena to be able to give an empathic hearing to patients who have NDE.     

Memory for timing visual and auditory signals in albino and pigmented rats

The authors hypothesized that during a gap in a timed signal, the time accumulated during the pregap interval decays at a rate proportional to the perceived salience of the gap, influenced by sensory acuity and signal intensity. When timing visual signals, albino (Sprague-Dawley) rats, which have poor visual acuity, stopped timing irrespective of gap duration, whereas pigmented (Long-Evans) rats, which have good visual acuity, stopped timing for short gaps but reset timing for long gaps. Pigmented rats stopped timing during a gap in a low-intensity visual signal and reset after a gap in a high-intensity visual signal, suggesting that memory for time in the gap procedure varies with the perceived salience of the gap, possibly through an attentional mechanism.     

A versatile microcomputer-based multiple-field tachistoscope

A newly introduced microcomputer in its most basic form provides a wide variety of stimulus display capabilities at an extremely low price. Several simple illustrative programs demonstrate its ability to present any number of visual stimuli in sequence and record response latencies, thus duplicating the functions of a multiple-field tachistoscope and associated response-recording instrumentation.     

Can Ziskin withstand his own criticisms? problems with his model of cross-examination

Ziskin has mounted a concerted attack on the scientific basis of psychology and psychiatry and their ability to provide expertise to the courts. He has assailed both the clinical methods and conclusions rendered by these mental health professionals. To rebut expert testimony, Ziskin has proposed general principles of cross-examination. We discuss the limitations of this model and provide an initial study of its effectiveness.     

Protein kinase a in major depression: the link between hypothalamic-pituitary-adrenal axis hyperactivity and neurogenesis

The latest and most generative biological theories of major depression center on two major hypotheses. The first focuses on the concept that hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis leads to many of the pathological changes in the brain that accompany major depression. The second posits that neurogenesis leads to the repair of depression-related injuries. These two hypotheses are complementary: the former alludes to the etiology or consequences of depression, while the latter suggests mechanisms of antidepressant action. Significant crosstalk occurs between these two systems at many levels. Protein kinase A (PKA) may play an important role in this crosstalk at the intracellular level of signaling cascades. PKA is involved in the formation of long-term potentiation and fear conditioning in response to stress. Chronic stress leads to the suppression of hippocampal activity, which may cause the hyperactivity of the HPA axis during melancholic depression. PKA is also involved in the stimulation of hippocampal neurogenesis after antidepressant treatment. In theory, neurogenesis may lead to the restoration of hippocampal function, and this may be the mechanism that leads to antidepressant-mediated normalization of HPA hyperactivity. Thus, PKA is active during processes that potentially lead to depression and other processes that lead to the resolution of the illness. These opposing processes may be mediated by separate PKA isozymes that activate two distinct pathways. This review highlights the dual role of this enzyme in two biological hypotheses pertaining to depression and its treatment.     

Three-dimensional spatial representation in freely swimming fish

Research on spatial cognition has focused on how animals encode the horizontal component of space. However, most animals travel vertically within their environments, particularly those that fly or swim. Pelagic fish move with six degrees of freedom and must integrate these components to navigate accurately—how do they do this? Using an assay based on associative learning of the vertical and horizontal components of space within a rotating Y-maze, we found that fish (Astyanax fasciatus) learned and remembered information from both horizontal and vertical axes when they were presented either separately or as an integrated three-dimensional unit. When information from the two components conflicted, the fish used the previously learned vertical information in preference to the horizontal. This not only demonstrates that the horizontal and vertical components are stored separately in the fishes’ representation of space (simplifying the problem of 3D navigation), but also suggests that the vertical axis contains particularly salient spatial cues—presumably including hydrostatic pressure. To explore this latter possibility, we developed a physical theoretical model that shows how fish could determine their absolute depth using pressure. We next considered full volumetric spatial cognition. Astyanax were trained to swim towards a reward in a Y-maze that could be rotated, before the arms were removed during probe trials. The subjects were tracked in three dimensions as they swam freely through the surrounding cubic tank. The results revealed that fish are able to accurately encode metric information in a volume, and that the error accrued in the horizontal and vertical axes whilst swimming in probe trials was similar. Together, these experiments demonstrate that unlike in surface-bound rats, the vertical component of the representation of space is vitally important to fishes. We hypothesise that the representation of space in the brain of vertebrates could ultimately be shaped by the number of the degrees of freedom of movement that binds the navigating animal.