Properties of spatial representations: Data from sighted and blind subjects

Five questions concerning the properties of spatial representations are explored. (1) How accurately does a spatial representation correspond to the true scene? (2) If inaccurate, how does it differ? (3) Are representations of a familiar scene more accurate than those of an unfamiliar one? (4) Do representations of a scene currently in view differ from those retained in memory? (5) Do the representations of the blind have properties comparable to those-of the sighted? Seven sighted and 7 highly mobile blind subjects, all familiar with a room, and 6 sighted subjects unfamiliar with it, were asked to estimate the absolute distances between 10 salient objects in the room. The 14 familiar subjects made their estimates twice: while they were in the room, and while they were remote from it. Regression analyses showed that the estimates of all subjects had strong metric properties, being linearly related to true distance, with a true zero point; and multidimensional scaling showed that all subjects produced distance estimates that could be scaled in two dimensions to closely match the actual locations of the objects. Familiarity had no effect. The effect of location of testing was the same for both the sighted and the blind: all subjects displayed better spatial knowledge when tested in the room; and all subjects underestimated true distance substantially when tested out of the room. The results showed no qualitative differences as a function of blindness, at least for these highly skilled blind travelers.     

The use of partial temporal information in dating personal events

Memory & Cognition - The use of different types of partial temporal information is shown to affect dating accuracy and the distribution of errors in event dating. Several different types of...     

Book reviews

The Popularization of Medicine 1650–1850 Roy Porter (ed.), 1992 London, Routledge pp. x + 296, £50 (hardback) ISBN 0415 07217 4

Quantum Mechanics: An Empiricist View Bas Van Fraassen, 1991 Clarendon Press, Oxford pp. 558, £17.50 (paperback), ISBN 019 8239807     

Social skills and depression in adolescent suicide attempters

The relationship among depression, social skills, and suicidal behavior was examined in a sample of 41 adolescents hospitalized in a general medical setting following a suicide attempt. These subjects were compared to 40 nonsuicidal psychiatrically hospitalized adolescents. Level of depression, assessed using the Children's Depression Inventory (CDI), and social skills, assessed via the Matson Evaluation of Social Skills with Youngsters (MESSY), were evaluated for all subjects. The suicide attempters and psychiatrically hospitalized patients were not found to differ on either the CDI or MESSY. However, multiple regression analyses revealed the factor scores of the MESSY to be related to depression in both patient groups. The data provide support for the relationship between social skills and depression. Results are also discussed in terms of the similarities between adolescent suicide attempters and nonsuicidal psychiatrically disturbed adolescents.     

Performance of criminal psychopaths on selected neuropsychological tests

Screening batteries of standard neuropsychological tests were administered to 2 different samples (Ns = 90 and 167) of male prison inmates. Scores on the revised Psychopathy Checklist were used to divide inmates in each sample into high, moderate, and low psychopathy groups. There were no group differences in test performance in either of the samples, even when the effects of self-reported psychopathology and substance abuse were taken into account. The overall prevalence of both test-specific and global neuropsychological impairment was low and did not vary significantly across the 3 groups. The results provide no support for traditional brain-damage explanations of psychopathy.     

Moral relativism and deontic logic

If a native of India asserts “Killing cattle is wrong” and a Nebraskan asserts “Killing cattle is not wrong”, and both judgments agree with their respective moralities and both moralities are internally consistent, then the moral relativist says both judgments are fully correct. At this point relativism bifurcates. One branch which we call content relativism denies that the two people are contradicting each other. The idea is that the content of a moral judgment is a function of the overall moral point of view from which it proceeds. The second branch which we call truth value relativism affirms that the two judgments are contradictory. Truth value relativism appears to be logically incoherent. How can contradictory judgments be fully correct? For though there will be a sense of correctness in which each judgment is correct — namely by that of being correct relative to the morality relative to which each was expressed — if contradictory, the judgments cannot both be true, and thus cannot both be correct in this most basic sense of correctness. We defend truth value relativism against this sort of charge of logical incoherence by showing it can be accommodated by the existing semantical metatheories of deontic logic. Having done this we go on to argue that truth value relativism is the best version of relativism.