Identification of biological neurons using adaptive observers

This paper is to investigate the use of adaptive observers for the modeling of biological neurons and networks. Assuming that a neuron can be modeled as a continuous-time nonlinear system, it is possible to determine its unknown parameters using adaptive observer, based on the concept of adaptive synchronization. The same technique can be extended for the identification of an entire biological neural network. Some conventional observer designs are studied in this paper and satisfactory results are obtained, yet with some restrictions. To further extend the applicability of adaptive observers for the modeling process, a new design is suggested. It is based on a combination of linear feedback control approach and the dynamical minimization algorithm. The effectiveness of the designed adaptive observer is confirmed with simulations.     

Fate or fight: Exploring the hedonic costs of competition

As a resource-allocation method, free competition is generally considered more efficient and fairer than binding assignment, yet individuals’ hedonic experiences in these different resource-allocation conditions are largely ignored. Using a minimalistic experimental simulation procedure, we compared participants’ hedonic experiences between a free-competition condition (in which participants could equally and freely compete for the superior resource) and a binding-assignment condition (in which the superior and inferior resources were unequally and irreversibly assigned to different participants). We found that individuals in the binding-assignment condition – even the disadvantaged ones – were happier than those in the free-competition condition. We attributed the effect to individuals’ peace of mind, and supported the peace-of-mind notion by identifying two moderators: ease of social comparison and enjoyability of the inferior resource. In sum, this research highlighted the hedonic aspects of resource allocation methods and identified when accepting one’s fate is hedonically better than fighting for the best.     

Resource allocation for visual metaphor processing: A study of political cartoons

ABSTRACT

This paper is a study of visual metaphor processing in political cartoons, while secondary task reaction time was used to assess resource allocation when processing three types of visual metaphors, namely juxtapositions, fusions and replacements. Participants viewed a series of visual metaphors. At various intervals, they were invited to push a button whenever a probe appeared. Reaction times to detect the probes were recorded. Subsequently, participants performed recall and recognition tasks. Results showed that participants reacted faster to each successive probe, while metaphor type had no influence on reaction times. Concerning the recall task, the percentage of correctly recalled items was significantly lower for juxtapositions compared to replacements; results for fusions were in between the two. Recognition scores for juxtapositions and fusions were lower than those for replacements. These findings are discussed in the framework of visual metaphors literature, thus providing empirical support to visual metaphor processing.     

Sustained attention can create an (illusory) experience of seeing dynamic change

Recent studies speculated that two types of change detection exist, one involving the experience of seeing dynamic change (change over brief interval), the other involving detecting a completed change (change over long interval), with only the former requiring sustained attention. To examine this supposition, a flicker change detection task was conducted in which the spatial location of objects was manipulated (shift, no-shift). In shift conditions, changed image display appeared in different locations than they did in the original display. The time interval separating images was manipulated (200 or 1000 ms). Results showed that a shift led to poor change detection only in the short interval condition. The performance decline by the image shift was not attenuated even when participants knew beforehand whether or not a shift would occur. Results indicate that sustained attention, which is sustained for a brief time, is related to the experience of seeing dynamic change.