Frontal-Lobe Involvement in Spatial Memory: Evidence from PET,fMRI, and Lesion Studies

Many studies have identified the prefrontal cortex as the brain area that is critical for spatial memory, both in humans and in other primates. Other studies, however, have failed to establish this relation. Therefore, the aim of this paper was to review the literature regarding the role of the human prefrontal lobe in spatial memory. This was done by examining the evidence obtained from neuropsychological patients and from studies using brain-imaging techniques (PET and fMRI). Evidence supporting the notion that the prefrontal cortex is extensively involved in spatial working memory was found. The majority of these studies, however, suggests that frontal-lobe involvement is not related to the type of material that is being processed (e.g., spatial vs. nonspatial), but to process-specific functions, such as encoding and retrieval. Theoretically, these functions could be linked to the central executive within Baddeley's working-memory model, or to recent theories that emphasize the various processes that play a role in working memory. Also, methodological issues were discussed. Further research is needed to enhance our understanding of the precise interaction of domain-specific and general processes.     

Onset of obsessive-compulsive disorder: premorbid conditions and prodromal phase

This article focuses on the clinical onset of obsessive-compulsive disorder (OCD), specifically addressing the age of onset, gradual and acute onset, and whether there are some types of premorbid conditions or a prodromal phase that predispose individuals to the onset of OCD. Clinical and epidemiological studies have come to different conclusions regarding age at onset as well as regarding differences between the sexes. Data gleaned from research to date have demonstrated a relationship between OCD and obsessive-compulsive personality disorder (OCPD), although OCPD does not appear to be the more prevalent personality disorder among patients with OCD. Preliminary research has suggested that Axis I disorders may predispose individuals to OCD onset; however, the significance of this relationship remains to be clarified. Evidence of the association between OCD and subthreshold obsessive-compulsive syndrome suggests that these disorders lie on a continuum of severity, with some cases developing OCD while others do not.     

The role of surface attraction in perceiving volumetric shape

Rock [1973, Orientation and Form (New York: Academic Press)] showed that form perception generally depends more on the orientation of a stimulus in world coordinates than on its orientation in retinal coordinates. He suggested that the assignment of an object's 'environmental orientation' depends on gravity, visual frame of reference, and the observer's ability to impose orientation along one axis or another. This paper shows that the assignment of environmental orientation and perceived 3-D form also depends on the relationship between an object and retinally adjacent surfaces in the scene to which it might be attached. Whereas previous examples have demonstrated effects of orientation on 2-D form, we show that orientation can affect the perceived intrinsic 3-D shape of a volume.     

The generic viewpoint assumption and Bayesian inference

The task of human vision is to reliably infer useful information about the external environment from images formed on the retinae. In general, the inference of scene properties from retinal images is not deductive; it requires knowledge about the external environment. Further, it has been suggested that the environment must be regular in some way in order for any scene properties to be reliably inferred. In particular, Knill and Kersten [1991, in Pattern Recognition by Man and Machine Ed. R J Watt (London: Macmillan)] and Jepson et al [1996, in Bayesian Approaches to Perception Eds D Knill, W Richards (Cambridge: Cambridge University Press)] claim that, given an 'unbiased' prior probability distribution for the scenes being observed, the generic viewpoint assumption is not probabilistically valid. However, this claim depends upon the use of representation spaces that may not be appropriate for the problems they consider. In fact, it is problematic to define a rigorous criterion for a probability distribution to be considered 'random' or 'regularity-free' in many natural domains of interest. This problem is closely related to Bertrand's paradox. I propose that, in the case of 'unbiased' priors, the reliability of inferences based on the generic viewpoint assumption depends partly on whether or not an observed coincidence in the image involves features known to be on the same object. This proposal is based on important differences between the distributions associated with: (i) a 'random' placement of features in 3-D, and (ii) the positions of features on a 'randomly shaped' and 'randomly posed' 3-D object. Similar considerations arise in the case of inferring 3-D motion from image motion.     

Transfer of newly acquired stimulus valence between identities in dissociative identity disorder (DID)

Patients with Dissociative Identity Disorder (DID) frequently report episodes of interidentity amnesia, that is amnesia for events experienced by other identities. The goal of the present experiment was to test the implicit transfer of trauma-related information between identities in DID. We hypothesized that whereas declarative information may transfer from one identity to another, the emotional connotation of the memory may be dissociated, especially in the case of negative, trauma-related emotional valence. An evaluative conditioning procedure was combined with an affective priming procedure, both performed by different identities. In the evaluative conditioning procedure, previously neutral stimuli come to refer to a negative or positive connotation. The affective priming procedure was used to test the transfer of this acquired valence to an identity reporting interidentity amnesia. Results indicated activation of stimulus valence in the affective priming task, that is transfer of emotional material between identities.     

Evaluative conditioning in social psychology: Facts and speculations

The aim of the present paper is to examine the contribution of evaluative conditioning (EC) to attitude formation theory in social psychology. This aim is pursued on two fronts. First, evaluative conditioning is analysed for its relevance to social psychological research. We show that conditioned attitudes can be acquired through simple co-occurrences of a neutral and a valenced stimulus. Moreover, we argue that conditioned attitudes are not confined to direct contact with a valenced stimulus, but can be formed and dynamically reformed indirectly, through association chains. Second, social research is examined in an effort to identify evaluative learning mechanisms. We suggest that several important phenomena in social psychology (e.g., ingroup favouritism, prejudice, name letter effect) are at least partly due to simple mechanisms of evaluative learning. The implications for attitude formation theory and for applied settings are discussed.     

On broadening the cognitive, motivational, and sociostructural scope of theorizing about gender development and functioning: comment on Martin, Ruble, and Szkrybalo (2002)

In their article on gender development, C. L. Martin, D. N. Ruble, and J. Szkrybalo (see record 2002-18663-003) contrasted their conception of gender development with that of social cognitive theory. The authors of this commentary correct misrepresentations of social cognitive theory and analyze the conceptual and empirical status of Martin et al.'s (2002) theory that gender stereotype matching is the main motivating force of gender development. Martin et al. (2002) based their claim for the causal primacy of gender self-categorization on construal of gender discrimination as rudimentary self-identity, equivocal empirical evidence, and dismissal of discordant evidence because of methodological deficiencies. The repeated finding that gendered preferences and behavior precede emergence of a sense of self is discordant with their theory. Different lines of evidence confirm that gender development and functioning are socially situated, richly contextualized, and conditionally manifested rather than governed mainly by an intrinsic drive to match stereotypic gender self-conception.     

Differential effects of cast shadows on perception and action

In two experiments we investigated the effects of cast shadows on different real-life tasks. In experiment 1, participants were required to make a speeded verbal identification of the target object (perceptual task), whereas in experiment 2 participants were required to reach for and grasp the target object (motor task). In both experiments real three-dimensional (3-D) objects were presented, one at a time, either with their own natural cast shadow (congruent condition) or with the cast shadow of a different object (incongruent condition). Shadows were cast either to the left or to the right of the object. We asked whether the features of the shadow (ie whether it is congruent or incongruent with the object, and whether it is cast to the left or to the right of the object) could influence perception and action differently. Results showed that cast shadows did not influence identification of real 3-D objects (experiment 1), but they affected movement kinematics, producing distractor-like interference, particularly on movement trajectory (experiment 2). These findings suggest a task-dependent influence of cast shadows on human performance. In the case of object-oriented actions, cast shadows may represent further affordances of the object, and as such compete for the control of the action.