Cognitive architecture of perceptual organization: from neurons to gnosons

What, if anything, is cognitive architecture and how is it implemented in neural architecture? Focusing on perceptual organization, this question is addressed by way of a pluralist approach which, supported by metatheoretical considerations, combines complementary insights from representational, connectionist, and dynamic systems approaches to cognition. This pluralist approach starts from a representationally inspired model which implements the intertwined but functionally distinguishable subprocesses of feedforward feature encoding, horizontal feature binding, and recurrent feature selection. As sustained by a review of neuroscientific evidence, these are the subprocesses that are believed to take place in the visual hierarchy in the brain. Furthermore, the model employs a special form of processing, called transparallel processing, whose neural signature is proposed to be gamma-band synchronization in transient horizontal neural assemblies. In neuroscience, such assemblies are believed to mediate binding of similar features. Their formal counterparts in the model are special input-dependent distributed representations, called hyperstrings, which allow many similar features to be processed in a transparallel fashion, that is, simultaneously as if only one feature were concerned. This form of processing does justice to both the high combinatorial capacity and the high speed of the perceptual organization process. A naturally following proposal is that those temporarily synchronized neural assemblies are “gnosons”, that is, constituents of flexible self-organizing cognitive architecture in between the relatively rigid level of neurons and the still elusive level of consciousness.     

Managing the death of close others: Evidence of higher valuing of ingroup identity in young adults who have experienced the death of a close other

The death of a close other (DOCO) is perhaps the most difficult experience that people endure. According to terror management theory (TMT), people manage the potentially terrorizing awareness of their mortality by immersing in cultural worldviews that allow them to feel like valuable members of a meaningful universe who may have some existence or trace after death. Although TMT has potential implications for understanding how people cope with DOCO, few studies have examined this possibility. We report results from four studies showing that, in line with TMT, students who experienced DOCO reported stronger valuing of their identification with their in-groups, which in turn was associated with higher levels of self-esteem. These findings shed new light on the social-psychological dynamics of DOCO.     

Experiencing double-bind conflict: A semantic differential assessment of interaction perceptions

Four interaction-perception perspectives of the fictitious target of a double-bind conflict were provided by four groups of subjects. The perspectives included perceptions of a daughter about herself and her father (the double-bind source), and her estimates of his perceptions of both himself and her. As predicted, the target saw herself as weak but “good”, and as cooperative and highly frustrated, while attributing all the opposite characteristics to the source, who was seen as strong but “bad”, and uncooperative and not frustrated. Further, it was found that she believed he saw himself as strong and very good, but frustrated and moderately cooperative. These observations are consistent with a hypothesis that double-bind experiences result in frustration and mixed feelings toward one's self and the source of the dilemma. It was also concluded that the target's belief that her father would not recognize her weakness, nor her cooperativeness, nor her frustration, and would disinterestedly evaluate her as neither good nor bad resulted from the inconsistent and contradictory communications which had contributed to the double bind.     

Symmetry and repetition in perspective

Although ecologically relevant, perspective views of symmetries and repetitions have hardly been investigated. Any symmetry or repetition that is not oriented orthogonally to the line of sight yields perspective distortions on the retina. In this study, these distortions are analyzed in terms of first-order structures (i.e., virtual lines between corresponding points) and second-order structures (i.e., correlation quadrangles formed by two virtual lines). In the literature, these structures have been proposed to guide the detection of fron to parallel symmetry and repetition. But what about perspective views? First, the analysis in this study shows that perspective distorts the retinal first-order and second-order structures of symmetry and repetition differently. Second, the results of two experiments on this distortion difference suggest that, in perspective views, symmetry and repetition detection is not preceded by normalization but occurs directly on the basis of the retinal first-order and second-order structures.     

Metrical information load of lines and angles in line patterns

Summary Acute angles and long lines are more complex than obtuse angels and short lines. This source of complexity is called metrical information, for which a measure was proposed by Leeuwenberg (1982). According to this measure, the metrical information of a static pattern is specified as the sum of the mechanical impulses necessary to move an object according to this pattern. The perceptual relevance of this metrical load was tested in an experiment in which judged complexities were gathered for a number of simple line patterns.     

An EMG-driven musculoskeletal model of the shoulder

This paper aims to develop an EMG-driven model of the shoulder that can consider possible muscle co-contractions. A musculoskeletal shoulder model (the original model) is modified such that measured EMGs can be used as model-inputs (the EMG-driven model). The model is validated by using the in-vivo measured glenohumeral-joint reaction forces (GH-JRFs). Three patients carrying instrumented hemi-arthroplasty were asked to perform arm abduction and forward-flexion up to maximum possible elevation, during which motion data, EMG, and in-vivo GH-JRF were measured. The measured EMGs were normalized and together with analyzed motions served as model inputs to estimate the GH-JRF. All possible combinations of input EMGs ranging from a single signal to all EMG signals together were tested. The 'best solution' was defined as the combination of EMGs which yielded the closest match between the model and the experiments. Two types of inconsistencies between the original model and the measurements were observed including a general GH-JRF underestimation and a GH-JRF drop above 90° elevation. Both inconsistencies appeared to be related to co-contraction since inclusion of EMGs could significantly (p<.05) improve the predicted GH-JRF (up to 45%). The developed model has shown the potential to successfully take the existent muscle co-contractions of patients into account.     

Sleep and Affective Brain Regulation

Rapidly emerging evidence continues to describe an intimate and causal relationship between sleep and affective brain regulation. These findings are mirrored by long‐standing clinical observations demonstrating that nearly all mood and anxiety disorders co‐occur with one or more abnormalities of sleep. This review aims to (1) provide a synthesis of recent human evidence describing affective brain and behavioral benefits of sleep when it is obtained, and conversely, detrimental impairments following a lack thereof, (2) set forth a rapid eye movement sleep hypothesis of affective brain homeostasis, optimally preparing the organism for next‐day social and emotional functioning, and (3) outline how this model may explain the prevalent relationships observed between sleep and affective disorders, including relevant treatment mechanisms, with a particular focus on post‐traumatic stress disorder (PTSD).