In the blink of an eye: Value and novelty drive saccades

Evidence accumulation is an essential component of value-based decisions. Recent human studies suggest that overt attention correlates with evidence accumulation necessary for optimal decisions. However, the influence of covert attention on decision-making remains relatively unexplored. To investigate this issue, two monkeys were trained to perform a decision-making task where they chose between two stimuli, which were either ‘Overtrained’ or learned that day (‘Novel’). Subjects could freely saccade during choice evaluation and indicated their decision by moving a joystick. Saccades were made within 170 ms of stimulus presentation and were strongly driven by both value and novelty, implying covert stimulus evaluation prior to saccade. This effect was strongest for ‘Overtrained’ choices, but rapidly emerged during learning of ‘Novel’ choices. Though novel stimuli attracted initial saccades, final decisions were guided only by value; implying attentional value comparison processes are at least partially dissociable from value comparison processes that govern final decisions. While subjects made highly optimal decisions, they frequently viewed only one stimulus; final choice was thus best explained by assuming covert evidence accumulation. Our results suggest that the primate brain contains multiple value comparison systems for guiding attention toward highly valuable or novel information while simultaneously optimizing final decision value

Muffled price signals: Household water demand under increasing-block prices

In many areas of the world, including large parts of the United States, scarce water supplies are a serious resource and environmental concern. The possibility exists that water is being used at rates that exceed what would be dictated by efficiency criteria, particularly when externalities are taken into account. Because of this, much attention has been given by policy makers and others to the use of various techniques of demand management, including requirements for the adoption of specific technologies and restrictions on particular uses. A natural question for economists to ask is whether price would be a more effective instrument to facilitate efficient management of water resources. As a first step in such an investigation, this paper draws upon a newly available set of detailed data to estimate econometrically the demand function for household use of urban water supplies. Because of the diverse multiple-block pricing structures that abound, estimation of this relationship poses some challenging and interesting problems

National environmental policy during the Clinton years

We review major developments in national environmental policy during the Clinton Administration, defining environmental policy to include not only the statutes, regulations, and policies associated with reducing pollution, but also major issues of public lands management and species preservation. We adopt economic criteria for policy assessment — principally efficiency, cost-effectiveness, and distributional equity. While the paper is primarily descriptive, we highlight a set of themes that emerge in the economics of national environmental policy over the past decade

Sustained attention and the flash grab effect

When a stationary target is briefly presented on top of a moving background as it reverses direction, the target is displaced perceptually in the direction of the upcoming motion (the flash grab effect). To determine the role of attention in this effect, we investigated whether the predictability of the location of the flash grab target modulates the illusion. First, we established that effect was weaker for spatially predictable targets. Next, we showed that the flash grab effect decreased for a narrower spatial spread of attention before the onset of the target and that it was smaller for left hemifield presentations than right. Finally, we demonstrated that diverting attention away from the target and the background motion decreases the flash grab effect. In the first two experiments, the decrease in the illusion could be attributed to either increased attention to the target or decreased attention to the motion; we assume that increasing attention to the target necessarily decreases attention to the motion. However, in the final experiment, the central task decreases attention to both the target and the motion. The results show a decrease in the illusion and that reveals that attention to the motion is the primary causal factor

Fake news and critical thinking in information evaluation

In the post-truth era we are constantly bombarded with “news” which is fabricated, distorted, and massaged information, published with the intention to deceive and mislead others. Such “news” has come to be known as “fake news”. The influence of fake news can have profound socio-political and cultural effects when translated into action. The ability to distinguish between real facts, fabricated stories, rumours, propaganda, or opinions is of paramount importance. The rapid proliferation of information through social media is now the norm. In this paper we consider the challenge of preparing students, in developing skills for recognising mis-information, dis-information and mal-information. We argue that critical thinking for evaluating information should now be considered a basic literacy, equally important to literacy itself, as well as information and information technology literacies. In this paper we revisit Bloom’s taxonomy of cognitive skills and represent what a learner can achieve at each level. We customise the traditional moral and ethical concepts suggested by the US Content Subcommittee of the ImpactCS Steering Committee to flag the ethical concerns over mis-information, dis-information and mal-information. We report on current levels of awareness and practices at the authors’ five higher education institutions, and reveal varying levels of awareness of the significance of critical literacy and different practices in each location. The paper concludes with an outline of future work

Motion-induced distortion of shape

Motion, position, and form are intricately intertwined in perception. Motion distorts visual space, resulting in illusory position shifts such as flash-drag and flash-grab effects. The flash-grab displaces a test by up to several times its size. This lets us use it to investigate where the motion-induced shift operates in the processing stream from photoreceptor activation to feature activation to object recognition. We present several canonical, highly familiar forms and ask whether the motion-induced shift operates uniformly across the form. If it did, we could conclude that the effect occurred after the elements of the form are bound. However, we find that motion-induced distortion affects not only the position, but also the appearance of briefly presented, canonical shapes (square, circle, and letter T). Features of the flashed target that were closest to its center were shifted in the direction of motion more than those further from its center. Outline shapes were affected more than filled shapes, and the strength of the distortion increased with the contrast of the moving background. This not only supports a nonuniform spatial profile for the motion-induced shift but also indicates that the shift operates before the shape is established, even for highly familiar shapes like squares, circles, and letters

High-Q terahertz Bragg resonances within a metal parallel plate waveguide

One-dimensional (1D) Bragg waveguides are demonstrated at terahertz (THz) frequencies. Lithographically made 1D symmetric and asymmetric dielectric gratings on metallized high conductivity Si chips are incorporated within metal parallel plate waveguides to form Bragg waveguides. These waveguides have high throughput and have Bragg resonances with linewidths approaching 6 GHz and Q as high as 430. These high-Q resonant Bragg waveguides are excellent structures for applications in THz sensing.Peer reviewedElectrical and Computer Engineerin

Design and implementation of a low-cost mechatronic shoe for biomechanical analysis of the human locomotion

In this paper the development of a low-cost and easy wearable mechatronic system for the measurement of ground reaction forces (GRF) for the biomechanical analysis of the human locomotion is presented. The system consists of an insole, a conditioning device for the signals produced by the sensors applied to the insole and a data acquisition system connected to a USB portable storage. The sensors applied to the insole can measure the reaction forces in the horizontal and vertical directions during locomotion. The prototype was validated by comparing the data from the sensors with the values obtained using a force platform

Ultrathin Oxide Films by Atomic Layer Deposition on Graphene

In this paper, a method is presented to create and characterize mechanically robust, free standing, ultrathin, oxide films with controlled, nanometer-scale thickness using Atomic Layer Deposition (ALD) on graphene. Aluminum oxide films were deposited onto suspended graphene membranes using ALD. Subsequent etching of the graphene left pure aluminum oxide films only a few atoms in thickness. A pressurized blister test was used to determine that these ultrathin films have a Young's modulus of 154 \pm 13 GPa. This Young's modulus is comparable to much thicker alumina ALD films. This behavior indicates that these ultrathin two-dimensional films have excellent mechanical integrity. The films are also impermeable to standard gases suggesting they are pinhole-free. These continuous ultrathin films are expected to enable new applications in fields such as thin film coatings, membranes and flexible electronics.Comment: Nano Letters (just accepted