DeLanda’s ontology: assemblage and realism

Manuel DeLanda is one of the few admitted realists in present-day continental philosophy, a position he claims to draw from Deleuze. DeLanda conceives of the world as made up of countless layers of assemblages, irreducible to their parts and never dissolved into larger organic wholes. This article supports DeLanda’s position as a refreshing new model for continental thought. It also criticizes his movement away from singular individuals toward disembodied attractors and topological structures lying outside all specific beings. While endorsing DeLanda’s realism, I reject his shift from the actual to the virtual.

Hiding and searching strategies of adult humans in a virtual and a real-space room

Adults searched for or cached three objects in nine hiding locations in a virtual room or a real-space room. In both rooms, the locations selected by participants differed systematically between searching and hiding. Specifically, participants moved farther from origin and dispersed their choices more when hiding objects than when searching for hidden objects. In addition, in both virtual and real-space rooms, prior experience in the hiding task increased the distance participants traveled from origin and the dispersion of their choices during searching. Furthermore, gender differences appeared in the virtual room but not in the real-space room. Specifically, during hiding females travelled farther from origin than males and during searching they dispersed their choices more than males. Overall, the results suggest that strategies used by adult humans for searching and caching are consistent with those seen in non-human animals and children.     

Hippocampus-dependent strategy choice predicts low levels of cell proliferation in the dentate gyrus

Neurogenesis continues to occur throughout life in the mammalian hippocampus. Previous research has suggested that the production of new neurons in the hippocampus during adulthood may be related to hippocampus-dependent learning and memory. However, the exact relationship between adult neurogenesis and learning and memory remains unclear. Here we investigated whether learning strategy selection is related to cell proliferation or to survival of new neurons in the hippocampus of adult male rats. We trained rats on alternating blocks of hippocampus-dependent (hidden platform) and hippocampus-independent (visible platform) versions of the Morris water task with the platform always in the same position. Following training, rats were given a probe session during which the platform was visible and in a novel location. Preferred strategy was determined by observing the initial swim path. Rats were classified as place strategy (hippocampus-dependent) users if they swam to the old platform location. Cue strategy (hippocampus-independent) users were classified as those rats that swam initially to the visible platform. Our results indicate that rats that preferentially used a place strategy had significantly lower cell proliferation than cue strategy users. However, there was no significant difference in cell survival or number of immature neurons between strategy user groups. These results suggest that low levels of cell proliferation in the dentate gyrus may be conducive or coincident with more efficient memory processing in the hippocampus.     

Damage to the retrosplenial cortex produces specific impairments in spatial working memory

Mounting evidence indicates that the retrosplenial cortex (RSP) has a critical role in spatial navigation. The goal of the present study was to characterize the specific nature of spatial memory deficits that are observed following damage to RSP. Rats with RSP lesions or sham lesions were first trained in a working memory task using an 8-arm radial arm maze. Rats were allowed 5 min to visit each arm and retrieve food pellets and a 5-s delay was imposed between arm choices. Consistent with previous research, rats with RSP damage committed more errors than controls. In particular, RSP-lesioned rats committed more errors of omission (failing to visit an arm of the maze), but there were no lesion effects on errors of commission (revisiting an arm). Neither group of rats exhibited a turn bias (i.e., always turning a certain direction when choosing an arm). At the end of the training phase of the experiment, both groups had reached asymptote and committed very few errors. In the subsequent test phase, a longer delay (30-s) was imposed during some sessions. Both control and RSP-lesioned rats continued to make few errors during sessions with the standard 5-s delay, but RSP-lesioned rats were impaired at the 30-s delay and committed more errors of commission, consistent with an increase in taxing spatial working memory.     

Measuring perceived ceiling height in a visual comparison task

When judging interior space, a dark ceiling is judged to be lower than a light ceiling. The method of metric judgments (e.g., on a centimetre scale) that has typically been used in such tasks may reflect a genuine perceptual effect or it may reflect a cognitively mediated impression. We employed a height-matching method in which perceived ceiling height had to be matched with an adjustable pillar, thus obtaining psychometric functions that allowed for an estimation of the point of subjective equality (PSE) and the difference limen (DL). The height-matching method developed in this paper allows for a direct visual match and does not require metric judgment. It has the added advantage of providing superior precision. Experiment 1 used ceiling heights between 2.90?m and 3.00?m. The PSE proved sensitive to slight changes in perceived ceiling height. The DL was about 3% of the physical ceiling height. Experiment 2 found similar results for lower (2.30?m to 2.50?m) and higher (3.30?m to 3.50?m) ceilings. In Experiment 3, we additionally varied ceiling lightness (light grey vs. dark grey). The height matches showed that the light ceiling appeared significantly higher than the darker ceiling. We therefore attribute the influence of ceiling lightness on perceived ceiling height to a direct perceptual rather than a cognitive effect.     

Social comparison processes in organizations

We systematically analyze the role of social comparison processes in organizations. Specifically, we describe how social comparison processes have been used to explain six key areas of organizational inquiry: (1) organizational justice, (2) performance appraisal, (3) virtual work environments, (4) affective behavior in the workplace, (5) stress, and (6) leadership. Additionally, we describe how unique contextual factors in organizations offer new insight into two widely studied sub-processes of social comparison, acquiring social information and thinking about that information. Our analyses underscore the merit of integrating organizational phenomena and social comparison processes in future research and theory.     

Virtual team leadership: The effects of leadership style and communication medium on team interaction styles and outcomes

This study investigated the effects of transformational and transactional leadership styles and communication media on team interaction styles and outcomes. Teams communicated through one of the following three ways: (a) face-to-face, (b) desktop videoconference, or (c) text-based chat. Results indicated that transformational and transactional leadership styles did not affect team interaction styles or outcomes; that the mean constructive interaction score was higher in FTF than videoconference and chat teams, but not significantly higher in videoconference than chat teams; and that teams working in richer communication media did not achieve higher task performance than those communicating through less rich media. Finally, mean team cohesion scores were higher in FTF and videoconference than chat teams, but not significantly higher in FTF than videoconference teams. These results provide further evidence that communication media do have important effects on team interaction styles and cohesion.     

Interaction between locale and taxon strategies in human spatial learning

Three computer-based experiments which tested human participants in a non-immersive virtual watermaze task sought to determine factors which dictate whether the presence of a visual platform disrupts locale learning and taxon learning. In Experiment 1, the visible platform disrupted locale but not taxon learning based on viewpoint-independent and viewpoint-dependent information, respectively. In Experiment 2, taxon learning based on non-geometric cues providing viewpoint-dependent information was disrupted by the visible platform when the cues required relational information to disambiguate them from other cues. Experiment 3 placed participants in an isosceles triangular pool. The presence of the visible platform did not disrupt the encoding of relational information provided by shape of the pool. These results support the notion that geometric cues are encoded in a separate module which is impenetrable to non-geometric cues not creating the shape of the environment.     

Planet Braitenberg: Experiments in virtual psychology

Braitenberg vehicles are simple robotic platforms, equipped with rudimentary sensor and motor components. Such vehicles have typically featured as part of thought experiments that are intended to show how complex behaviours are apt to emerge from the interaction of inner control mechanisms with aspects of bodily structure and features of the wider (extra-agential) environment. The present paper describes a framework for creating Braitenberg-like vehicles, which is built on top of a widely used and freely available game engine, namely, the Unity game engine. The framework can be used to study the behaviour of virtual vehicles within a multiplicity of virtual environments. All aspects of the vehicle’s design, as well as the wider virtual environment in which the vehicle is situated, can be modified during the design phase, as well as at runtime. The result is a general-purpose simulation capability that is intended to provide the foundation for studies in so-called computational situated cognition—a field of study whose primary objective is to support the computational modelling of cognitive processes associated with the physically-embodied, environmentally-embedded, and materially-extended mind.