Cortical maps for hearing and egocentric selection for self-organization

The auditory cortex of the mustached bat shows complex multiple frequency maps, because cortical neurons in several areas are tuned to particular combinations of signal elements. Different types of combination-sensitive neurons form computational maps in which information-bearing parameters for echolocation (biosonar) are represented systematically. Neuronal response properties and multiple-frequency and computational maps were considered to be created solely by divergent-convergent interactions of neurons in the 'ascending' system. However, we have found that the 'corticofugal' system also plays an important role. Neurons in an iso-best frequency (or echo delay) 'minicolumn' of the auditory cortex augment the auditory responses of subcortical neurons tuned to that frequency (or echo delay) and sharpen their tuning. At the same time, they reduce the response and shift the tuning of subcortical neurons tuned to other frequencies (or echo delays) away from the best frequency (or delay) of the cortical neurons. Cortical neurons mediate a highly focused positive feedback, incorporated with widespread lateral inhibition, via corticofugal projections. This 'egocentric selection' is expected to play an important role in self-organizing the central auditory system.     

“Are False Memories Permanent?”: An Investigation of the Long-Term Effects of Source Misattributions

With growing concerns over children's suggestibility and how it may impact their reliability as witnesses, there is increasing interest in determining the long-term effects of induced memories. The goal of the present research was to learn whether source misattributions found by Ceci, Huffman, Smith, and Loftus (1994) caused permanent memory alterations in the subjects tested. When 22 children from the original study were reinterviewed 2 years later, they recalled 77% of all true events. However, they only consented to 13% of all false events, compared to the 22% false consent rate (among the same subset of children) found by Ceci et al. (1994). Additionally, while children remained accurate in their recall of true events (they maintained assents 78% of the time), they “recanted” their earlier false consents 77% of the time, after the 2-year delay. Implications of these findings for child witnesses and the legal system are discussed.     

Lateralized Changes in Regional Cerebral Blood Flow during Performance of Verbal and Facial Recognition Tasks: Correlations with Performance and “Effort”

Functional neuroimaging has been used to investigate neural substrates of mnemonic processes, and cerebral blood flow (CBF) measures have been sensitive to activation with memory tasks. Studies of memory with two-dimensional¹³³Xenon clearance techniques found that word and face recognition tasks produced contralateral CBF changes in mid-temporal cortical regions. This study replicated the activation paradigm, expanding to the three-dimensional resolution of positron emission tomography (PET). Word and face recognition, and a control baseline task were administered to 19 healthy right-handed volunteers (11 men, 8 women) during successive 10 min PET¹⁵O-water measures of CBF. Quantitative CBF rates were calculated with the arterial input function and the equilibrium model. Redistributions of blood flow were compared across tasks using both absolute and relative (region/whole brain) CBF.Replicating the¹³³Xenon clearance findings, CBF was “appropriately” lateralized during task performance (left–right for words > left–right for faces) in the mid-temporal region. Contrary to predictions, the recognition tasks did not activate expected mesolimbic or prefrontal areas. The task-induced CBF changes also correlated with performance. Bilateral CBF in mid-temporal and parahippocampal gyrus regions of interest correlated with the ability to correctly identify word targets (sensitivity). Left-lateralized CBF in the amygdala and hippocampus correlated with better word sensitivity as well as specificity (ability to correctly reject foils). Complementally, right-lateralized CBF in the parahippocampal gyrus correlated with better face specificity performance. In addition, left-lateralized CBF in the amygdala and right-lateralized CBF in the parahippocampal gyrus and hippocampus correlated with “mental effort” indices (task performance relative to basal ability) for word and face memory tasks, respectively. Thus, whereas this recognition task showed the expected lateralized increase in the mid-temporal region and not in frontal and limbic areas, lateralized activation in some of these areas was associated with better performance. Exploratory analyses on other regions showed lateralized changes in one additional temporal region, the occipital-temporal, and several limbic regions.     

Zhuangzi and relativistic scepticism

Chad Hansen is one of the strongest proponents of the view that the important second chapter of Zhuangzi's Inner Chapters (The Qi Wu Lun) reveals Zhuangzi to be a relativistic sceptidst. Hansen argues that Zhuangzi is a sceptic because he is first and foremost a relativist. Hansen's argument is essentially that Zhuangzi's perspectivism, his belief that one's linguistic and conceptual perspective determines what one claims to know, makes him a thorough going relativist and sceptic. I agree that Zhuangzi is a perspectivist, but disagree with Hansen's portrayal of him as a relativistic sceptic. I first show that there is an important ambiguity in Hansen's argument. I then proceed to argue that important passages in the Qi Wu Lun (in particular the butterfly dream passage,) reveal serious problems with Hansen's interpretation of Zhuangzi's philosophical stance, I maintain that Zhuangzi is neither a sceptic nor a perspectival relativist. He is rather a perspectival realist.     

Referenzsemantik in der Partnermodellierung

How can we explain that an assertion on something perceived can be understood in the same manner by somebody who cannot perceive that scene? This problem bases the interest in computational linguistics in how listener modeling could possibly be harmonized with reference semantics. Mental images substituting real perception appear as a way out. The architecture of the listener model has to be adapted to the creation and use of such pictorial data structures. Furthermore, the relation between the latter and a verbal (i. e., propositional) representation must be understood. The resulting architecture of a listener model with reference semantics can be employed to solve communicational problems from three general classes in a better way, as is demonstrated by an example implementation.     

Towards an Interactive Acculturation Model: A Social Psychological Approach

The first part of this paper proposes a continuum of ideological premises that seeks to account for the broad range of immigrant integration policies adopted by Western democratic states. In the second part, a review of Social Psychological models of immigrant acculturation strategies demonstrates the need to explain more clearly the interactive nature of immigrant and host community relations. The Interactive Acculturation Model (IAM) presented next proposes that relational outcomes are the product of the acculturation orientations of both the host majority and immigrant groups as influenced by state integration policies. The model makes predictions regarding the acculturation combinations most likely to produce consensual, problematic, and conflictual relational outcomes between immigrants and members of the host community. Social psychological research is needed to test the validity of the IAM model empirically.     

Motor skill acquisition and retention as a function of average feedback, summary feedback, and performance variability

Summary feedback involves withholding feedback from subjects until the last trial in a block is completed, and then presenting feedback about each trial. A variation of this method, called average feedback (Young & Schmidt, 1992), presents subjects with only the mean of the trial block. We investigated whether these methods have similar effects on acquisition and retention of a simple motor skill. Five groups of subjects (n = 16 per group) performed 60 acquisition trials of an aiming task involving both spatial and temporal accuracy. We presented average and summary feedback based on either 5-trial blocks or 15-trial blocks and compared these schedules with every-trial feedback. During acquisition, all groups improved with practice, with a slight tendency for the every-trial condition to have less absolute error than the longer summary and average conditions. Analysis of delayed no-feedback retention tests, however, revealed a strong advantage for the 5-trial summary and average conditions compared with the every-trial condition. In addition, we found that for long blocks of acquisition trials without augmented feedback, the performance variability of those trials was associated with retention performance. Results are discussed in terms of how these different manipulations may make feedback less useful during acquisition, but foster the use of certain information processing activities that enhance overall learning.     

How (not) to evaluate the comparability of MMPI and MMPI-2 profile configurations: a reply to Humphrey and Dahlstrom

Humphrey and Dahlstrom (1995) presented a study on the comparability of MMPI/MMPI-2 (Butcher, Dahlstrom, Graham, Tellegen, & Kaemmer, 1989) profiles in which they concluded that "the bases for clinical interpretation derived from the MMPI and MMPI-2 profiles were sufficiently at variance to require different conclusions" [sic] (p. 2). In this brief critique, we identify procedural and data-analytical deficiencies that invalidate Humphrey and Dahlstrom's argument. Their blanket recommendation based on this argument, namely, that clinicians routinely plot both MMPI and MMPI-2 profiles, is unwarranted.