1,721,120 research outputs found
Visual Creativity Across Cultures: A Comparison Between Italians and Japanese
No full textCulture-related differences in visual creativity were investigated, comparing Italian and Japanese participants in terms of divergent (figural completion task) and product-oriented thinking (figural combination task). Visual restructuring ability was measured as the ability to reinterpret ambiguous figures and was included as a covariate. Results showed that in divergent thinking, Italians only outperformed Japanese participants in elaboration and in product-oriented thinking in terms of originality of products. Visual restructuring ability was found to play a key role both in originality and practicality of products. Both groups scored the same in terms of fluency, originality, and flexibility of visual divergent thinking, as well as in term of practicality of creative products. These findings are consistent with the idea that Italians and Japanese have the same creative potential, although from the early stages of the design Japanese seem to show a greater tendency to take practicality constraints into account when creating in the visual domain
Photometric, figural and crossmodal factors in the perception of transparency and in depth stratification of layers.
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Style and spectral power: Processing of abstract and representational art in artists and non-artists
No full textWe investigated cortical activity in response to abstract and representational paintings in artists and non-artists. Participants engaged in visual inspection of works of art and recalled them immediately afterwards through mental imagery. Meanwhile, we recorded their EEG, and calculated the power of their alpha band and theta band activity afterwards. In accordance with previous studies, theta band and alpha band power differed between artists and non-artists; these differences were found to depend, however, on the abstract or representational character of the paintings. Differences between abstract and representational art, and between inspection and imagery, occurred in alpha band power for non-artists only and in theta band power for artists. These results were taken to suggest that effects in artists reflect sustained focused attention and perceptual flexibility; in non-artists motivation and engagement with the task. The results were essentially whole-head, despite the local character of the measurement. © 2010 a Pion publication
Rapid switching and complementary evidence accumulation enable flexibility of an all-or-none global workspace for control of attentional and conscious processing: a reply to Wyble et al
Full text linkAlthough attentional (e.g. [1]) and conscious (e.g. [2]) processing limitations have been widely acknowledged as interdependent (e.g. [3–5]), a unifying theory has been lacking. As an attempt to bridge these domains, we recently proposed the Theory of Attention and Consciousness (TAC; [6]). TAC provides a unified neurocognitive account of several phenomena associated with visual search, attentional blink (AB), and working memory (WM) consolidation. Wyble et al. [7] commented on our TAC proposal, focusing on WM consolidation and AB effects.
With respect to WM consolidation, which corresponds to short-term memory (STM) encoding in their framework, Wyble et al. [7] observe that there is mounting evidence for parallel processing of multiple targets. In the lag-1 sparing condition of the AB paradigm, two targets are apparently encoded together [8]. Global workspace (GW) models (e.g. [2]) face particular difficulties in accounting for such evidence, given that their processing limitations are based on a strict winner-take-all principle (however, see [9] for a neural model enabling parallel target encoding in the GW). Wyble et al. [7] acknowledge that while retaining the notion of GW, TAC attempts to go beyond such models, in particular by introducing an ‘intermediate buffer’ mechanism. This mechanism operates in tandem with a winner-take-all competition in the GW between higher order executive routers for attentional selection and consolidation in WM. Instead, in their previously proposed Episodic Simultaneous Type Serial Token (eSTST) model [10–12], competition for resources between encoding in STM and attentional selection is not winner-take-all but leads to attenuation of these processes. Wyble et al. [7] emphasize that, unlike TAC, the eSTST model permits parallel encoding of multiple targets into STM.
First of all, we note that the TAC as described in Raffone et al. [6], in spite of the claims in Wyble et al.'s [7] comment, is in principle neutral with respect to serial versus parallel consolidation in WM. These issues are not explicitly addressed in the current, first formulation of the theory, which is to be developed further in order to account for a broader set of data, including divided attention and multitasking paradigms (e.g. [13]). Wyble et al. [7] claim that parallelism favours encoding of multiple targets in WM in discrete attentional episodes. TAC enables a form of parallel ‘episodic’ representation for encoding in WM. Specifically, multiple targets represented in the intermediate buffer may be consolidated through repeated shifts in the processing priority of different targets, each of which lasts a few tenths of milliseconds, with a mechanism based on nested slow and fast processing cycles. This mechanism would be revealed electrophysiologically through phase–amplitude coupling. The role of this mechanism in AB conditions has recently been demonstrated [14]. This mechanism reconciles winner-take-all and seriality of fast processing cycles with parallel representation of multiple targets within slow processing cycles. TAC would thus entail a universal mechanism at multiple processing levels: attentional filtering, WM consolidation and WM maintenance.
Some recent evidence has emerged from a visual search task in which multiple items need to be remembered, thus requiring resources for both attentional selection and WM consolidation [15]. Eye-tracking data from this study suggest that these processes cannot be achieved in parallel, but need to be handled sequentially. Eye-movements to the next target were delayed when visual WM capacity was exceeded, which suggests that when extra resources were needed for memory representation, this competed with attentional selection. Consistently with the above-mentioned mechanism, the delay is of the order of tenths of milliseconds.
Let us now consider the first empirical benchmark that Wyble et al. [7] consider unattainable for TAC, namely that providing a cue during the deepest part of the AB has a facilitatory effect on the following target (T2) [16] and no effect on accuracy of reporting the first target (T1) in the rapidly presented series. Although TAC proposes a winner-take-all or all-or-none competition between higher-order executive routers for consolidation in WM and attentional selection in the GW, it also includes complementary graded and ongoing evidence accumulation processes driving such competition, and assumes the possibility of rapid and reversible switches between the ignition (activation) of either the attentional selection or the WM consolidation router. In TAC, such reversibility is central to account for trials in which the AB does not occur even with lags such as lag-2 and lag-3, in terms of a sparing recovery process [6]. Because of these mechanisms, the model is able to account for the first empirical benchmark. For our part, we are worried about the apparently rigid notion of ‘attentional episode’ in the eSTST model, which would appear to face difficulty in accounting for this sparing recovery.
In reference to the second specific empirical benchmark that Wyble et al. [7] deem unattainable for TAC, i.e. the observation that, in event-related potentials (ERP), the onset of P3 (a component assumed to be related to WM consolidation) is not delayed at lag-1 when compared with lag-8 (fig. 2 in Wyble et al.'s comment [7], from [17]). However, the effect permits an alternative account, motivated by the more persistent positivity of the P3 wave in lag-1 when compared with lag-8 conditions in fig. 2 [7]. In terms of the GW mechanisms assumed in TAC, this effect would reflect a prolonged activation of the GW router for WM consolidation. This prolonged activation is needed in the competition for resources with the router for attentional selection. This explanation is in accordance with the observation that the effect of spatio-temporal selection decreases with practice in the AB task [18]. This alternative account appears also more consistent with the electrophysiological evidence of late conscious access markers [19], with a latency of about 300 ms, which in our view suggests that consolidation for encoding in WM (STM) is initiated rather than completed around that time. Furthermore, in the same fig. 2 [7], we observe a pronounced difference in amplitude of the P3 component for T1 and T2 with lag-8. In our view, such evidence can be hardly explained if not in terms of a higher-order competition mechanism between routers for WM consolidation and attentional selection. Specifically, TAC would predict a lower accumulation of evidence (cortical inputs) needed to reactivate the router for WM consolidation for T2, related to a reduced P3 amplitude for T2 when compared with T1 with lag-8, owing to the earlier activation of the same router for T1. Thus, a priming effect would be established between T1 and T2 presentations with lag-8, in terms of residual (slowly decaying) graded activation feeding the (all-or-none) higher-order router for WM consolidation in the GW, implicated for the consolidation of both targets.
We agree with Wyble et al. [7] that conscious processing and WM encoding for relevant targets need to be completed as fast as possible. The occurrence of multiple stages of processing in TAC ensures that relevant processing steps for target perception occur before consolidation for encoding in WM. Moreover, the processes of evidence accumulation and ignition driving attentional selection and WM consolidation in the GW should enable prioritarization of the most relevant processing operation at any given time in a task.
Wyble et al. [7] conclude their comment by asking about the adaptive utility of suppressing attention during encoding, and observe that preventing interference from feature and proto-object representations as claimed in TAC seems an insufficient answer, also in the light of the evidence of parallel target processing with lag-1 sparing. First of all, we note that processing two targets with lag-1 sparing may implicate costs and errors [20], also depending on the relative strength of the targets. Moreover, given the strong amplification assumed to take place in the GW during conscious access, with a strong selective feedback towards neurons in posterior cortex involved in the representation of the accessed target and its features (e.g. [2]), any concomitant amplification for attentional selection in posterior cortex could give rise to spurious activations and target detections when incoming task-irrelevant stimuli share features with the accessed target.
Finally, the processes, mechanisms and computations proposed in TAC need to be specified and evaluated in working model implementations and simulations, in the light of behavioural, electrophysiological and neurophysiological data. These simulations will also enable a detailed comparison with other simulation-based models of the AB and WM encoding, including eSTST [10–12] and ViSA [9]. Given the broad explanatory scope of TAC, the simulations also need to deal with a range of other phenomena and effects, such as in visual search and dual-performance tasks.status: Publishe
Modeling of Complex Reaction Systems: Steam Cracker
No full textSteam pyrolysis of ethane and naphtha is an important chemical bulk process. It produces ethylene and propylene, which are important base chemicals. In order to be competitive, crackers have to be operated at near optimal conditions. Hence, a simulation program of the process, particularly of the pyrolysis is very helpful. KTI uses and licenses such a program called SPYRO*. Development of this program has started over 20 years ago. Consequently, it uses a closed model. It has been the objective of this study to investigate the feasibility of the development of an open version of SPYRO. Here open means that the equations are written in residual form .This enhances the flexibility of the program very much. For our studies we have used the model of Froment for ethane cracking because the documentation to make an open SPYRO model was insufficient. This Froment model has been modified as to improve the modeling of the bends. It has been checked, whether the solution of this model would pose any problems. It was found that the index might become more than 1 during integration. As yet no sound physical explanation has been found for this phenomena. It also follows from investigation of the index that a start-up problem of the numerical integration exists for the original set of differential equations. We have found a more elegant method to circumvent this problem than Froment. Moreover, we were able to solve the set of equations for bad initial conditions (equal to the boundary conditions). The ordinary differential equations of the model are turned into algebraic equations using orthogonal collocation on finite elements. This allows the model to be solved with an equation solver. The results were compared with various commercial numerical integrators. Excellent agreement was found for limited numbers of sections and collocation points. The speed of solution of the linearized set of modal equations depends on the size, the sparsity and structure of the Jacobian. The latter has an enormous effect on the fill-in of the L and U decomposition matrices. We found a very satisfying structure by modification of the equations and proper arrangement in the Jacobian. On the basis of the above results we may draw the following conclusions regarding the feasibility of the development of an Open SPYRO model. Unfortunately we had to use a simple model of Froment rather than the SPYRO equations themselves. Nevertheless, we have concluded that such a development is feasible. Within a reasonable time an accurate solution will be found even with bad starting values. The computation time can be further reduced with a smart initialization procedure.Chemical EngineeringApplied Science
Abilities within and across visual and verbal domains: How specific is their influence on creativity?
No full textDoes visual creativity rely predominantly on visual abilities and verbal creativity on verbal abilities, or is there a cross-over between the domains? Participants (N=25) performed several visual tasks and verbal ability tests, as well as visual and verbal creativity tests. Both correlation and multidimensional scaling analyses were performed. Visual creativity was found to be related to visual abilities, in particular to restructuring. Verbal creativity was related to verbal ability scores, such as vocabulary and comprehension, but also by vividness scores of the visual imagery questionnaire. These findings are consistent with the notion that visual creativity is largely domain-and task-specific, whereas verbal creativity, even though mostly domain-specific, may, to some extent, be sensitive to processes in the visual domain as well. © Taylor & Francis Group, LLC
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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