Plan-based generalization shapes local implicit adaptation to opposing visuomotor transformations

The human ability to use different tools demonstrates our capability of forming and maintaining multiple, context-specific motor memories. Experimentally, this has been investigated in dual adaptation, where participants adjust their reaching movements to opposing visuomotor transformations. Adaptation in these paradigms occurs by distinct processes, such as strategies for each transformation or the implicit acquisition of distinct visuomotor mappings. Although distinct, transformation-dependent aftereffects have been interpreted as support for the latter, they could reflect adaptation of a single visuomotor map, which is locally adjusted in different regions of the workspace. Indeed, recent studies suggest that explicit aiming strategies direct where in the workspace implicit adaptation occurs, thus potentially serving as a cue to enable dual adaptation. Disentangling these possibilities is critical to understanding how humans acquire and maintain motor memories for different skills and tools. We therefore investigated generalization of explicit and implicit adaptation to untrained movement directions after participants practiced two opposing cursor rotations, which were associated with the visual display being presented in the left or right half of the screen. Whereas participants learned to compensate for opposing rotations by explicit strategies specific to this visual workspace cue, aftereffects were not cue sensitive. Instead, aftereffects displayed bimodal generalization patterns that appeared to reflect locally limited learning of both transformations. By varying target arrangements and instructions, we show that these patterns are consistent with implicit adaptation that generalizes locally around movement plans associated with opposing visuomotor transformations. Our findings show that strategies can shape implicit adaptation in a complex manner. NEW & NOTEWORTHY Visuomotor dual adaptation experiments have identified contextual cues that enable learning of separate visuomotor mappings, but the underlying representations of learning are unclear. We report that visual workspace separation as a contextual cue enables the compensation of opposing cursor rotations by a combination of explicit and implicit processes: Learners developed context-dependent explicit aiming strategies, whereas an implicit visuomotor map represented dual adaptation independent from arbitrary context cues by local adaptation around the explicit movement plan.

Plan-based generalization shapes local implicit adaptation to opposing visuomotor transformations

The human ability to use different tools demonstrates our capability of forming and maintaining multiple, context specific motor memories. Experimentally, this ability has been investigated in dual adaptation, where participants adjust their reaching movements to opposing visuomotor transformations. Adaptation in these paradigms occurs by distinct processes, i.e. the development of explicit aiming strategies for each transformation and/or the implicit acquisition of distinct visuomotor mappings. The presence of distinct, transformation-dependent aftereffects has been interpreted as support for the latter. Alternatively, however, distinct aftereffects could reflect adaptation of a single visuomotor map, which is locally adjusted in different regions of the workspace. Indeed, recent studies suggest that explicit aiming strategies direct where in the workspace implicit adaptation occurs.Disentangling these possibilities is critical to understanding how humans acquire and maintain separate motor memories for different skills and tools. We therefore investigated generalization of explicit and implicit adaptation to different directions after participants practiced two opposing cursor rotations, which were associated with separate visual workspaces. Whereas participants learned to compensate opposing rotations by explicit strategies that were specific to the visual workspace cue, aftereffects were not sensitive to visual workspace cues. Instead, aftereffects displayed bimodal generalization patterns that appeared to reflect locally limited learning of both transformations. By varying target arrangements and instructions, we show that these generalization patterns are consistent with implicit adaptation that generalizes locally around (explicit) movement plans associated with opposing visuomotor transformations. Our findings show that strategies can shape implicit adaptation in a complex manner.New & NoteworthyVisuomotor dual adaptation experiments have identified contextual cues that enable learning of separate visuomotor mappings, but little is known about the underlying representations of learning. We report that visual workspace separation as a contextual cue enables participants to compensate opposing cursor rotations by a combination of explicit and implicit processes: Learners developed context-dependent explicit aiming strategies while an implicit visuomotor map represented dual adaptation independent from context by local adaptation around the explicit movement plan.

Sharp Bounds for the General Sum-Connectivity Indices of Transformation Graphs

Given a graph G, the general sum-connectivity index is defined as χα(G)=∑uv∈E(G)dGu+dGvα, where dG(u) (or dG(v)) denotes the degree of vertex u (or v) in the graph G and α is a real number. In this paper, we obtain the sharp bounds for general sum-connectivity indices of several graph transformations, including the semitotal-point graph, semitotal-line graph, total graph, and eight distinct transformation graphs Guvw, where u,v,w∈+,-.

Die Einflüsse der Brentano’schen Intentionalitätskonzeptionen auf den frühen Husserl

Both the current research literature and a tradition stemming from Husserl himself agree that it was Brentano’s notion of intentionality which „gave rise“ to Husserl’s phenomenology. I rely on extensive primary materials, including unpublished sources from four archives, to revisit this thesis. Already a survey of the historical circumstances of Brentano’s second decade in Vienna, when Husserl studied under him, hints at possible discrepancies in the reception of Brentano’s thought, which are further deepened by the editing policy employed by his orthodox students. I analyze an unpublished lecture manuscript of Brentano to find three different notions of intentionality, including a strikingly a-phenomenological one, which I then relate to the discussion by modern scholarship and try to identify those notions of intentionality which were encountered by Husserl as a student of Brentano. Given this heterogeneous matrix of influences, it is far from surprising that a closer look at Husserl’s philosophical juvenilia shows that he misunderstood Brentano’s notion of intentionality and attempted to employ it in a different theoretical context (maybe motivated by an idiosyncratic notion of inner perception). Finally, the notion of intentionality Husserl later attributed to Brentano was probably mitigated to him by indirect sources, including lecture manuscripts copied by the extravagant and less-know student of Brentano, Hans Schmidkunz, and a debate between a contemporary logician Christoph Sigwart and Brentano’s orthodox disciples. The analysis of these transmission mechanisms could reveal a distinct transformation which proved to be instrumental in the development of Husserl’s transcendental phenomenology. The allegedly decisive influence of Brentano’s notion of intentionality at Husserl thus seems to consist in a productive misunderstanding (which apparently corresponds to Brentano’s surprisingly dismissive evaluation of Husserl after Husserl’s departure from Vienna).

Die Drehmaschinen in der Geschichte der Psychiatrie

The history of the rotatory machine shows a distinct transformation during its short-lived use in psychiatric therapy from about 1806 to 1836. Initially a variety of hypotheses were offered to explain its mode of action. Gradually the use of the method became a plain disciplinary measure. The technical features of the machine also changed. The adherents of both psychic and somatic treatment in psychiatry did not object to the method. Obviously, as a result of Conolly's no-restraint the use of the machine fell into disrepute. The scant case histories suggest that the machine was mainly used as a means of intimidation and deterrent. It is worth to be remembered that humane physicians in the middle of the 20th century still used deterring methods such as the aversion treatment of alcoholics.

Sedimentation and Transformation in Organizational Change: The Case of Canadian Law Firms

This paper identifies two archetypes in large Canadian law firms to show how ideas of professionalism and partnership are changing, due in part to shifts in discourses in the wider institutional context. These changes in discourse themselves alter the interpretation of organizational structures and systems. This theme is explored through the concept of tracks and sedimentation. We explore the emergence of an organizational archetype that appears not to be secure, and which results in sedimented structures with competitive commit ments. The geological metaphor of sedimentation allows us to consider a dia lectical rather than a linear view of change. Case studies of two law firms show how one archetype is layered on the other, rather than representing a distinct transformation where one archetype sweeps away the residues of the other.