Joseph A. Heng


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Heng

First Name

Joseph A.

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0000-0002-3643-4623

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2019 - 201912020 - 20254
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Publications1 - 5 of 5
  • Neural Mechanisms Underlying Cognitive Limitations
    Item type: Doctoral Thesis
    Heng, Joseph A. (2023)
    Our brains are finite. This limitation entails that human decision-making cannot be perfect. However, it may be optimal given its restrictions. In this thesis, we consider resource limitations to study the brain and its behavior. In the first project, we study how humans perceives the number of elements in a set. In particular, we develop a model based on efficient coding given limited resources. Based on this model, we investigate which is the computational goal that underlies human perception. We find that human behavior is best captured by a model that not only maximizes accuracy, but also economizes on resources to represent the environment. In the second project, we investigate how humans deal with time limitations in perception. In particular, we investigate how humans estimate the number of elements in a set under limited time. We find that a parsimonious model based on sequential-encoding and Bayesian-decoding reproduces the variabilities and biases of human behavior. This model better captures human behavior than a thermodynamically inspired model of information processing constraints. In the third project, we study a way in which the brain deals with representing a stimuli rich world with finite resources by studying non-spatial attention. In particular, we study the role of fluctuations in excitability states in the prefrontal cortex. With a combination of neuroimaging and neurostimulation, we find these fluctuations to be causally involved in the top-down control of non-spatial attention. Finally, in the last project, we study a disorder related to decision-making by studying obesity. In particular, we investigate how dietary decision-making differs between individuals with and without obesity. We find no difference in between groups when participants rate their willingness to eat different food items. However, we observe differences in the influence of different nutritional and non-nutritional attributes as well as overt attention on food choices Altogether, this work shows the relevance of considering resource limitations to understand behavior and the brain.
  • Efficient sampling and noisy decisions
    Item type: Journal Article
    Heng, Joseph A.; Woodford, Michael; Polania, Rafael Hernan (2020)
    eLife
    Human decisions are based on finite information, which makes them inherently imprecise. But what determines the degree of such imprecision? Here, we develop an efficient coding framework for higher-level cognitive processes in which information is represented by a finite number of discrete samples. We characterize the sampling process that maximizes perceptual accuracy or fitness under the often-adopted assumption that full adaptation to an environmental distribution is possible, and show how the optimal process differs when detailed information about the current contextual distribution is costly. We tested this theory on a numerosity discrimination task, and found that humans efficiently adapt to contextual distributions, but in the way predicted by the model in which people must economize on environmental information. Thus, understanding decision behavior requires that we account for biological restrictions on information coding, challenging the often-adopted assumption of precise prior knowledge in higher-level decision systems.
  • Weber’s Law: A Mechanistic Foundation after Two Centuries
    Item type: Other Journal Item
    Brus, Jeroen; Heng, Joseph A.; Polania, Rafael Hernan (2019)
    Trends in Cognitive Sciences
  • Efficient numerosity estimation under limited time
    Item type: Journal Article
    Heng, Joseph A.; Woodford, Michael; Polania, Rafael Hernan (2025)
    PLoS Computational Biology
    The ability to rapidly estimate non-symbolic numerical quantities is a well-conserved sense across species with clear evolutionary advantages. However, despite its importance, this sense is surprisingly imprecise and biased, and a formal explanation for this seemingly irrational behavior remains unclear. We develop a unified normative theory of numerosity estimation that parsimoniously incorporates in a single framework information processing constraints alongside (i) Brownian diffusion noise to capture the effects of time exposure of sensory information, (ii) logarithmic encoding of numerosity representations, and (iii) optimal inference via Bayesian decoding. We show that for a given allowable biological capacity constraint our model naturally endogenizes time perception during noisy efficient encoding to predict the complete posterior distribution of numerosity estimates. This model accurately predicts many features of human numerosity estimation as a function of temporal exposure, indicating that humans can rapidly and efficiently sample numerosity information over time. Additionally, we demonstrate how our model fundamentally differs from a thermodynamically-inspired formalization of bounded rationality, where information processing is modeled as acting to shift away from default states. The mechanism we propose is the likely origin of a variety of numerical cognition patterns observed in humans and other animals.
  • Causal phase-dependent control of non-spatial attention in human prefrontal cortex
    Item type: Journal Article
    Brus, Jeroen; Heng, Joseph A.; Beliaeva, Valeriia; et al. (2024)
    Nature Human Behaviour
    Non-spatial attention is a fundamental cognitive mechanism that allows organisms to orient the focus of conscious awareness towards sensory information that is relevant to a behavioural goal while shifting it away from irrelevant stimuli. It has been suggested that attention is regulated by the ongoing phase of slow excitability fluctuations of neural activity in the prefrontal cortex, a hypothesis that has been challenged with no consensus. Here we developed a behavioural and non-invasive stimulation paradigm aiming at modulating slow excitability fluctuations of the inferior frontal junction. Using this approach, we show that non-spatial attention can be selectively modulated as a function of the ongoing phase of exogenously modulated excitability states of this brain structure. These results demonstrate that non-spatial attention relies on ongoing prefrontal excitability states, which are probably regulated by slow oscillatory dynamics, that orchestrate goal-oriented behaviour.
Publications1 - 5 of 5