69,141 research outputs found
Human scalp potentials reflect a mixture of decision-related signals during perceptual choices
Single-unit animal studies have consistently reported decision-related activity mirroring a process of temporal accumulation of sensory evidence to a fixed internal decision boundary. To date, our understanding of how response patterns seen in single-unit data manifest themselves at the macroscopic level of brain activity obtained from human neuroimaging data remains limited. Here, we use single-trial analysis of human electroencephalography data to show that population responses on the scalp can capture choice-predictive activity that builds up gradually over time with a rate proportional to the amount of sensory evidence, consistent with the properties of a drift-diffusion-like process as characterized by computational modeling. Interestingly, at time of choice, scalp potentials continue to appear parametrically modulated by the amount of sensory evidence rather than converging to a fixed decision boundary as predicted by our model. We show that trial-to-trial fluctuations in these response-locked signals exert independent leverage on behavior compared with the rate of evidence accumulation earlier in the trial. These results suggest that in addition to accumulator signals, population responses on the scalp reflect the influence of other decision-related signals that continue to covary with the amount of evidence at time of choice
Quantum Theory and Human Perception of the Macro-World
We investigate the question of 'why customary macroscopic entities appear to
us humans as they do, i.e. as bounded entities occupying space and persisting
through time', starting from our knowledge of quantum theory, how it affects
the behavior of such customary macroscopic entities, and how it influences our
perception of them. For this purpose, we approach the question from three
perspectives. Firstly, we look at the situation from the standard quantum
angle, more specifically the de Broglie wavelength analysis of the behavior of
macroscopic entities, indicate how a problem with spin and identity arises, and
illustrate how both play a fundamental role in well-established experimental
quantum-macroscopical phenomena, such as Bose-Einstein condensates. Secondly,
we analyze how the question is influenced by our result in axiomatic quantum
theory, which proves that standard quantum theory is structurally incapable of
describing separated entities. Thirdly, we put forward our new 'conceptual
quantum interpretation', including a highly detailed reformulation of the
question to confront the new insights and views that arise with the foregoing
analysis. At the end of the final section, a nuanced answer is given that can
be summarized as follows. The specific and very classical perception of human
seeing -- light as a geometric theory -- and human touching -- only ruled by
Pauli's exclusion principle -- plays a role in our perception of macroscopic
entities as ontologically stable entities in space. To ascertain quantum
behavior in such macroscopic entities, we will need measuring apparatuses
capable of its detection. Future experimental research will have to show if
sharp quantum effects -- as they occur in smaller entities -- appear to be
ontological aspects of customary macroscopic entities.Comment: 28 page
Consentaneous agent-based and stochastic model of the financial markets
We are looking for the agent-based treatment of the financial markets
considering necessity to build bridges between microscopic, agent based, and
macroscopic, phenomenological modeling. The acknowledgment that agent-based
modeling framework, which may provide qualitative and quantitative
understanding of the financial markets, is very ambiguous emphasizes the
exceptional value of well defined analytically tractable agent systems. Herding
as one of the behavior peculiarities considered in the behavioral finance is
the main property of the agent interactions we deal with in this contribution.
Looking for the consentaneous agent-based and macroscopic approach we combine
two origins of the noise: exogenous one, related to the information flow, and
endogenous one, arising form the complex stochastic dynamics of agents. As a
result we propose a three state agent-based herding model of the financial
markets. From this agent-based model we derive a set of stochastic differential
equations, which describes underlying macroscopic dynamics of agent population
and log price in the financial markets. The obtained solution is then subjected
to the exogenous noise, which shapes instantaneous return fluctuations. We test
both Gaussian and q-Gaussian noise as a source of the short term fluctuations.
The resulting model of the return in the financial markets with the same set of
parameters reproduces empirical probability and spectral densities of absolute
return observed in New York, Warsaw and NASDAQ OMX Vilnius Stock Exchanges. Our
result confirms the prevalent idea in behavioral finance that herding
interactions may be dominant over agent rationality and contribute towards
bubble formation.Comment: 17 pages, 6 figures, Gontis V, Kononovicius A (2014) Consentaneous
Agent-Based and Stochastic Model of the Financial Markets. PLoS ONE 9(7):
e102201. doi: 10.1371/journal.pone.010220
- …