Pattern separation, pattern completion, and new neuronal codes within a continuous CA3 map

The hippocampal CA3 subregion is critical for rapidly encoding new memories, which suggests that neuronal computations are implemented in its circuitry that cannot be performed elsewhere in the hippocampus or in the neocortex. Recording studies show that CA3 cells are bound to a large degree to a spatial coordinate system, while CA1 cells can become more independent of a map-based mechanism and allow for a larger degree of arbitrary associations, also in the temporal domain. The mapping of CA3 onto a spatial coordinate system intuitively points to its role in spatial navigation but does not directly suggest how such a mechanism may support memory processing. Although bound to spatial coordinates, the CA3 network can rapidly alter its firing rate in response to novel sensory inputs and is thus not as strictly tied to spatial mapping as grid cells in the medial entorhinal cortex. Such rate coding within an otherwise stable spatial map can immediately incorporate new sensory inputs into the two-dimensional matrix of CA3, where they can be integrated with already stored information about each place. CA3 cell ensembles may thus support the fast acquisition of detailed memories by providing a locally continuous, but globally orthogonal representation, which can rapidly provide a new neuronal index when information is encountered for the first time. This information can be interpreted in CA1 and other downstream cortical areas in the context of less spatially restricted information.     

Book review

This article suggests that envy is entwined with leadership in a number of complex and potentially problematic ways. It examines how aspects such as skill, power, authority, and prestige that are associated with leadership may evoke the envy of subordinates and colleagues. Envy may also be stirred up in the leader s family, friends, and colleagues outside the organization. Equally, leaders themselves may be prone to feeling envious of subordinates, colleagues, and others who they feel may threaten their position. Based on research using psychoanalytic concepts, it is suggested that because envy is so painful to bear it is often consigned to the unconscious, so that those who are envious are unaware or only partly aware of the extent and nature of their feelings. This can result in the subtle, indirect and often insidious expression of envy which undermines leadership and interferes with the effective running of the organization.     

Seeing structure: Shape skeletons modulate perceived similarity

An intrinsic part of seeing objects is seeing how similar or different they are relative to one another. This experience requires that objects be mentally represented in a common format over which such comparisons can be carried out. What is that representational format? Objects could be compared in terms of their superficial features (e.g., degree of pixel-by-pixel overlap), but a more intriguing possibility is that they are compared on the basis of a deeper structure. One especially promising candidate that has enjoyed success in the computer vision literature is the shape skeleton—a geometric transformation that represents objects according to their inferred underlying organization. Despite several hints that shape skeletons are computed in human vision, it remains unclear how much they actually matter for subsequent performance. Here, we explore the possibility that shape skeletons help mediate the ability to extract visual similarity. Observers completed a same/different task in which two shapes could vary either in their skeletal structure (without changing superficial features such as size, orientation, and internal angular separation) or in large surface-level ways (without changing overall skeletal organization). Discrimination was better for skeletally dissimilar shapes: observers had difficulty appreciating even surprisingly large differences when those differences did not reorganize the underlying skeletons. This pattern also generalized beyond line drawings to 3-D volumes whose skeletons were less readily inferable from the shapes’ visible contours. These results show how shape skeletons may influence the perception of similarity—and more generally, how they have important consequences for downstream visual processing.

     

Event models and the fan effect

The current study explored the persistence of event model organizations and how this influences the experience of interference during retrieval. People in this study memorized lists of sentences about objects in locations, such as “The potted palm is in the hotel.” Previous work has shown that such information can either be stored in separate event models, thereby producing retrieval interference, or integrated into common event models, thereby eliminating retrieval interference. Unlike prior studies, the current work explored the impact of forgetting up to 2 weeks later on this pattern of performance. We explored three possible outcomes across the various retention intervals. First, consistent with research showing that longer delays reduce proactive and retroactive interference, any retrieval interference effects of competing event models could be reduced over time. Second, the binding of information into events models may weaken over time, causing interference effects to emerge when they had previously been absent. Third, and finally, the organization of information into event models could remain stable over long periods of time. The results reported here are most consistent with the last outcome. While there were some minor variations across the various retention intervals, the basic pattern of event model organization remained preserved over the two-week retention period.     

The psychoanalytic assumption of the primary process: extrapsychoanalytic evidence and findings

No evidence for an assumption of a theory can be gained by data derived from methods dependent on that theory. Three experiments, using methods independent of psychoanalysis, test the psychoanalytic posit that primary process exists as a formal mental mode distinct from secondary process. The three experiments, using a nonpsychoanalytic index for primary process, test for a preponderance of primary process organization in three areas in which Freud observed primary process: (1) in unconscious mental states and during implicit tasks; (2) in the mental productions of preschool children; and (3) in anxiety states, as these are typically associated with unconscious conflict. All three experiments show significant results in favor of the primary process. Further, the three experiments taken together, because they account for seemingly disparate data, lend further credence to the original assumption. These positive results suggest that primary process may be more important than even Freud suspected. Perhaps it is the basic mental organization in many nonhuman mammals and some birds. Primary process organization may also underlie aspects of such basic psychological operations as generalizations in conditioning and assessments-in-action, as opposed to judgments proper, about how one would act. Finally, primary process may play a key role in drive activity. Three types of experiments are proposed to test these far-reaching applications of the primary process concept.     

Interactionism,haecceities, and the pairing argument

Interactionists hold that non-spatial objects (e.g. minds) causally interact with physical objects. Interactionists have traditionally grappled with the puzzle of how such interaction is possible. More recently, Jaegwon Kim has presented interactionists with a more daunting threat: the pairing argument, which purports to refute interactionism by showing that non-spatial objects cannot stand in causal relations. After reviewing that argument, I develop a challenge to it on behalf of the interactionist. The challenge poses a dilemma: roughly, either haecceities exist or they do not. I argue that the pairing argument fails in either case. While the challenge does not explain exactly how the pairing argument goes wrong, it shows that the argument fails. The challenge also explains the difficulty in pinpointing the pairing argument’s failure: exactly how the pairing argument fails depends on difficult issues concerning the nature of objects.     

Elaboration, organization, and the self-reference effect in memory

Relating information to the self (self-referent encoding) has been shown to produce better recall than purely semantic encoding. This finding has been interpreted as demonstrating that self-reference produces a more elaborate memory trace than semantic encoding, and it has been cited frequently as evidence that the self is one of the most highly elaborated structures in memory. The experiments reported in this article challenge this interpretation of the self-reference effect by demonstrating that self-referent and semantic encodings produce virtually identical free recall levels if they are first equated for the amount of organization they encourage. On the basis of our findings we conclude the following: Organization, not elaboration, is responsible for the superior recall performance obtained when information is encoded self-referentially, and organization is not a necessary component of self-referent encoding and can be orthogonally varied within self-referent and semantic encoding tasks. Finally, we discuss how a single-factor theory based on organization can account for many of the self-referent recall findings reported in the literature.     

Can connectionist models of phonology assembly account for phonology?

Connectionist models have gained considerable success as accounts of how printed words are named. Their success challenges the view of grapheme-to-phoneme correspondences (GPCs) as rules. By extension, however, this challenge is sometimes interpreted also as evidence against linguistic rules and variables. This inference tacitly assumes that the generalizations inherent in reading (specifically, GPCs) are similar in their scope to linguistic generalizations and that they are each reducible to token associations. I examine this assumption by comparing the scope of generalizations required for mapping graphemes to phonemes and several linguistic phonological generalizations. Marcus (1998b) distinguishes between two types of generalizations: those that fall within a model’s training space and those that exceed it. The scope of generalizations is determined by the model’s representational choices— specifically, the implementation of operations over mental variables. An analysis of GPCs suggests that such generalizations do not appeal to variables; hence, they may not exceed the training space. Likewise, certain phonological regularities, such as syllable phonotactic constraints and place assimilation, may be captured by an associative process. In contrast, other phonological processes appeal to variables; hence, such generalizations potentially exceed the training space. I discuss one such case, the obligatory contour principle. I demonstrate that speakers conform to this constraint and that their behavior is inexplicable by the statistical structure of the language. This analysis suggests that, unlike GPCs, phonological generalizations may exceed the training space. Thus, despite their success in modeling GPCs, eliminative connectionist models of phonology assembly may be unable to provide a complete account for phonology. To the extent that reading is subject to phonological constraints, its modeling may require implementing operations over variables.     

USING RANDOM RATHER THAN FIXED EFFECTS MODELS IN META-ANALYSIS: IMPLICATIONS FOR SITUATIONAL SPECIFICITY AND VALIDITY GENERALIZATION

Combining statistical information across studies (i.e., meta-analysis) is a standard research tool in applied psychology. The most common meta-analytic approach in applied psychology, the fixed effects approach, assumes that individual studies are homogeneous and are sampled from the same population. This model assumes that sampling error alone explains the majority of observed differences in study effect sizes and its use has lead some to challenge the notion of situational specificity in favor of validity generalization. We critique the fixed effects methodology and propose an advancement–the random effects model (RE) which provides estimates of how between-study differences influence the relationships under study. RE models assume that studies are heterogeneous since they are often conducted by different investigators under different settings. Parameter estimates of both models are compared and evidence in favor of the random effects approach is presented. We argue against use of the fixed effects model because it may lead to misleading conclusions about situational specificity.     

Assessing clinically relevant perceptual organization with multidimensional scaling techniques

Multidimensional scaling (MDS) techniques provide a promising measurement strategy for characterizing individual differences in cognitive processing, which many clinical theories associate with the development, maintenance, and treatment of psychopathology. The authors describe the use of deterministic and probabilistic MDS techniques for investigating numerous aspects of perceptual organization, such as dimensional attention, perceptual correlation, within-attribute organization, and perceptual variability. Additionally, they discuss how formal quantitative models can be used, in conjunction with MDS-derived representations of individual differences in perceptual organization, to test theories about the role of cognitive processing in clinically relevant phenomena. They include applied examples from their work in the areas of eating disorders and sexual coercion.     

Phenomenal Concepts and Higher-Order Experiences

Relying on a range of now-familiar thought-experiments, it has seemed to many philosophers that phenomenal consciousness is beyond the scope of reductive explanation. (Phenomenal consciousness is a form of state-consciousness, which contrasts with creature-consciousness, or perceptual -consciousness. The different forms of state-consciousness include various kinds of access-consciousness, both first-order and higher-order–see Rosenthal, 1986; Block, 1995; Lycan, 1996; Carruthers, 2000. Phenomenal consciousness is the property that mental states have when it is like something to possess them, or when they have subjectively-accessible feels; or as some would say, when they have qualia (see fn. l below).) Others have thought that we can undermine the credibility of those thought-experiments by allowing that we possess purely recognitional concepts for the properties of our conscious mental states. This paper is concerned to explain, and then to meet, the challenge of showing how purely recognitional concepts are possible if there are no such things as qualia –in the strong sense of intrinsic (non relational, non-intentional) properties of experience. It argues that an appeal to higher-order experiences is necessary to meet this challenge, and then deploys a novel form of higher-order thought theory to explain how such experiences are generated.     

The influence of learning methods on collaboration: prior repeated retrieval enhances retrieval organization, abolishes collaborative inhibition, and promotes post-collaborative memory

Research on collaborative memory has unveiled the counterintuitive yet robust phenomenon that collaboration impairs group recall. A candidate explanation for this collaborative inhibition effect is the disruption of people's idiosyncratic retrieval strategies during collaboration, and it is hypothesized that employing methods that improve one's organization protects against retrieval disruption. Here it is investigated how one's learning method during the study phase--defined as either repeatedly studying or repeatedly retrieving information--influences retrieval organization and what effects this has on collaborative recall and post-collaborative individual recall. Results show that repeated retrieval consistently eliminated collaborative inhibition. This enabled participants to gain the most from re-exposure to materials recalled by their partners that they themselves did not recall and led to improvements in their individual memory following collaboration. This repeated retrieval advantage stemmed from the preferential manner in which this learning method strengthened retrieval organization. Findings are also discussed that reveal a relationship between retrieval organization and the interaction observed between learning method and short versus long delay seen in the testing effect literature. Finally, results show that the elusive benefits of cross-cuing during collaboration may be best detected with a longer study-test delay. Together, these findings illuminate when and how collaboration can enhance memory.     

Interlinking physical beliefs: children's bias towards logical congruence

Young children's na?ve beliefs about physics are commonly studied as isolated pieces of knowledge. The current paper takes a different approach. It asks whether preschoolers interlink individual beliefs into larger configurations or Gestalts. Such Gestalts bring together knowledge such as how an object's mass relates to its sinking speed, how an object's volume relates to its sinking speed, and how mass and volume are correlated. The particular form of organization explored here is referred to as logical congruence, the logical correspondence in directions among three physical relations. Are children's guesses about one physical relation congruent with their beliefs about the other two relations? And can they learn a congruent set of relations more readily than an incongruent set? Two different physical domains were explored, one in which children commonly hold pre-existing beliefs, and one in which they are likely to lack such beliefs. The results in both domains show a strong bias towards congruent knowledge configurations in young children. These findings may explain children's difficulties learning inherently incongruous concepts such as density.     

My evangelical conviction

There are three things that may serve to disrupt the casual habits of intellect operative within a majority of studies that address American religion: (1) poesis must be practiced as a challenge to flat-footed analyses invested in common-sense literacy; (2) there must be an open and honest discussion of how scholars conceive of the characters they study and how they represent those subjects in print or other media; and (3) subtle attention must be paid to issues of discourse, that is, to issues of how people make themselves up even as they are made up by ideas, concepts, and words that have nothing essentially to do with them.     

Cognitive suppression of tilt sensations during linear horizontal self-motion in the dark

On the basis of models of otolith functioning, one would expect that, during sinusoidal linear self-motion in darkness, percepts of body tilt are experienced. However, this is normally not the case, which suggests that the otoliths are not responsive to small deviations from the vertical of the gravito-inertial force vector acting on them. Here we show that this is incorrect. Subjects usually know on what kind of linear motion device they are (going to be) moved, having seen it prior to experimentation. This may result in a cognitive suppression of such otolith responses. In the present study, subjects were kept completely unaware of how they were moved and were asked to report on how they thought they moved. About 50% of the reports included tilt percepts almost immediately. It is concluded that this reveals the presence of otolith responsiveness to even small and short-lived deviations of the gravito-inertial force vector from verticality, a responsiveness which is suppressed when (prior) cognitions exist that the motion path is purely in the horizontal plane.     

Encoding, consolidation, and retrieval of contextual memory: differential involvement of dorsal CA3 and CA1 hippocampal subregions

Studies on human and animals shed light on the unique hippocampus contributions to relational memory. However, the particular role of each hippocampal subregion in memory processing is still not clear. Hippocampal computational models and theories have emphasized a unique function in memory for each hippocampal subregion, with the CA3 area acting as an autoassociative memory network and the CA1 area as a critical output structure. In order to understand the respective roles of the CA3- and CA1-hippocampal areas in the formation of contextual memory, we studied the effects of the reversible inactivation by lidocaine of the CA3 or CA1 areas of the dorsal hippocampus on acquisition, consolidation, and retrieval of a contextual fear conditioning. Whereas infusions of lidocaine never impaired elementary tone conditioning, their effects on contextual conditioning provided interesting clues about the role of these two hippocampal regions. They demonstrated first that the CA3 area is necessary for the rapid elaboration of a unified representation of the context. Secondly, they suggested that the CA1 area is rather involved in the consolidation process of contextual memory. Third, they showed that CA1 or CA3 inactivation during retention test has no effect on contextual fear retrieval when a recognition memory procedure is used. In conclusion, our findings point as evidence that CA1 and CA3 subregions of the dorsal hippocampus play important and different roles in the acquisition and consolidation of contextual fear memory, whereas they are not required for context recognition.     

Stimulant effects in attention deficit hyperactivity disorder: theoretical and empirical issues

The explanatory utility of a theory or model of ADHD or any disorder depends fundamentally on its capacity to address issues of causality. What causes a particular child to develop ADHD? What mechanisms are responsible for temporal and setting-related variations in symptom severity, and how are these mechanisms affected by pharmacological intervention? And, what processes determine whether gains in one domain will propagate across one or more others? It should be evident from the foregoing discussion that comprehensive answers to such questions are most likely to emerge through implementation of research strategies that (a) integrate biological and psychological levels of explanation, (b) permit analysis of causal hypotheses, and (c) address mechanisms involved in both etiology and mediation of treatment response. Although extant neurobiological studies of ADHD are as compelling as they are exciting, they are limited by a troubling reductionistic emphasis. The predominant animal models focus on a narrow range of behaviors that are presumed to be central to ADHD because of the topographic similarity they bear to those represented by the diagnostic criteria incorporated into the diagnostic nomenclature. These models would become increasingly valuable to the extent that future research examined the extent to which ecologically relevant behaviors (e.g., social behavior) are compromised in the animal strains and whether the observed compromises are parallel to the correlates of ADHD observed in humans. Similarly, human molecular genetic studies have provided a glimpse into the possible role that genes related to dopaminergic neurotransmission may play in the etiology of ADHD. Yet, the features of ADHD have been conceptualized in these investigations as a unitary collection of characteristics, and this has precluded analysis of what specific syndromal feature (if any single one) is affected by the implicated genes. It is intriguing to speculate whether varying combinations of genes governing properties of DA receptors and reuptake molecules are associated with different patterns of symptom severity or responses to stimulant medications. As testing procedures for determining genotypes with respect to these features become more affordable and available, it should become increasingly feasible to examine such issues empirically. Research on the utility of stimulant drugs as a treatment for ADHD also has yielded useful information. Although the effects of MPH are of short duration, the breadth of their impact is impressive. The clinical effectiveness of these medications is no longer in doubt, and patterns of relations among outcome measures represent a potentially fruitful target of scientific inquiry. Finally, data supporting a neurobiological substrate for ADHD, evidence indicating that task and setting variables moderate the expression of the syndrome's diagnostic features (see Barkley, 1998, for a review), and the causal emphasis of the conceptual model with which the discussion began collectively argue for a diathesis-stress conception of the syndrome. And, as foregoing comments make clear, task and setting variables and the mechanisms through which they influence symptom expression are as important to the phenomenon as are neurobiological predisposing causes. This has significant implications for assessment strategies employed in diagnosis and evaluation of treatment-outcome. Specifically, it suggests that theory-based experimental manipulations of task and setting variables designed to impose challenge on hypothesized core features of the disorder are more likely to yield insights into the causal mechanisms governing behavioral organization in affected children than strategies emphasizing static identification of diagnostic correlates. It is hoped that such an approach will accelerate the discovery of increasingly effective assessment and intervention strategies.