Cortical dynamics of contextually cued attentive visual learning and search: spatial and object evidence accumulation

How do humans use target-predictive contextual information to facilitate visual search? How are consistently paired scenic objects and positions learned and used to more efficiently guide search in familiar scenes? For example, humans can learn that a certain combination of objects may define a context for a kitchen and trigger a more efficient search for a typical object, such as a sink, in that context. The ARTSCENE Search model is developed to illustrate the neural mechanisms of such memory-based context learning and guidance and to explain challenging behavioral data on positive-negative, spatial-object, and local-distant cueing effects during visual search, as well as related neuroanatomical, neurophysiological, and neuroimaging data. The model proposes how global scene layout at a first glance rapidly forms a hypothesis about the target location. This hypothesis is then incrementally refined as a scene is scanned with saccadic eye movements. The model simulates the interactive dynamics of object and spatial contextual cueing and attention in the cortical What and Where streams starting from early visual areas through medial temporal lobe to prefrontal cortex. After learning, model dorsolateral prefrontal cortex (area 46) primes possible target locations in posterior parietal cortex based on goal-modulated percepts of spatial scene gist that are represented in parahippocampal cortex. Model ventral prefrontal cortex (area 47/12) primes possible target identities in inferior temporal cortex based on the history of viewed objects represented in perirhinal cortex.     

TEM observation of oxide scale formed on a Ti–Al–Zr alloy oxidized at 360°C in alkaline steam

Ti–Al–Zr alloy has been oxidized at 360°C in alkaline steam at a pressure of 10.3?±?0.7?MPa. Cross-sectional transmission electron microscopy (TEM) observations indicated that the oxide scale of Ti–Al–Zr alloy was composed of outer and inner subscales, in which the outer layer consists of anatase-TiO₂ and the inner layer a mixture of TiO and Ti₂O. The thickness of the Ti₂O, TiO and anatase-TiO₂ were approximately 50, 100 and 400?nm, respectively. These results were confirmed by X-ray energy dispersive spectrometry (EDS) measurements. The enhanced corrosion of titanium alloys in LiOH solution is attributed to a high hexagonal Ti₂O to tetragonal TiO₂ phase transformation rate induced by the substitution of Li⁺ for Ti⁴⁺ in the oxide layer.     

The Effects of Artist Adoration and Perceived Risk of Getting Caught on Attitude and Intention to Pirate Music in the United States and Taiwan

Piracy is the greatest threat facing the global music industry today. This study explores the effects of artist adoration and the perceived risk of being caught on the attitude and intention to engage in pirating a digital song among college students. The moderating effect of cultural environment factor is also examined. Experiments using between-group factorial designs were conducted in the United States and Taiwan. The results show that perceived risk of getting caught and cultural environment are important factors that can significantly affect the attitude and intention toward downloading unauthorized music. In addition, a two-way (Perceived Risk × Culture) and a three-way interaction in the model are also observed.     

Intuitive Conceptions of Dead Persons' Mentality: A Cross-Cultural Replication and More

Jesse Bering (2002) investigated how American university students in an interview task conceived of dead persons' mentality immediately after death. He found that different categories of mental states or capacities were conceived differently: psychobiological and perceptual states ceased, whereas emotional, desire, and epistemic states continued. Our Study 1 was a replication of Bering's experiment in a different cultural setting, in which the subjects were Chinese undergraduate students. A similar pattern of results was found. In Study 2, instead of being asked about a dead person's various mental states immediately following the death, participants were asked to judge a dead person's mental states after the person had been dead for 2 days. The overall pattern of participants' responses was not affected by this manipulation, but they did show an increase in attributions of certain mental states to dead agnostics. In addition, a more refined breakdown of responses revealed that individuals tended to judge that, upon death, visual and auditory perception continued, whereas olfactory and gustatory sensation ceased.     

Kinematic property of target motion conditions gaze behavior and eye-hand synergy during manual tracking

This study investigated how frequency demand and motion feedback influenced composite ocular movements and eye-hand synergy during manual tracking. Fourteen volunteers conducted slow and fast force-tracking in which targets were displayed in either line-mode or wave-mode to guide manual tracking with target movement of direct position or velocity nature. The results showed that eye-hand synergy was a selective response of spatiotemporal coupling conditional on target rate and feedback mode. Slow and line-mode tracking exhibited stronger eye-hand coupling than fast and wave-mode tracking. Both eye movement and manual action led the target signal during fast-tracking, while the latency of ocular navigation during slow-tracking depended on the feedback mode. Slow-tracking resulted in more saccadic responses and larger pursuit gains than fast-tracking. Line-mode tracking led to larger pursuit gains but fewer and shorter gaze fixations than wave-mode tracking. During slow-tracking, incidences of saccade and gaze fixation fluctuated across a target cycle, peaking at velocity maximum and the maximal curvature of target displacement, respectively. For line-mode tracking, the incidence of smooth pursuit was phase-dependent, peaking at velocity maximum as well. Manual behavior of slow or line-mode tracking was better predicted by composite eye movements than that of fast or wave-mode tracking. In conclusion, manual tracking relied on versatile visual strategies to perceive target movements of different kinematic properties, which suggested a flexible coordinative control for the ocular and manual sensorimotor systems.     

Dynamic Regulation Responding to an External Stimulus: A Differential Equation Model

This study examines the dynamic regulation process responding to an external stimulus. The damped oscillator model has been used to describe this process. However, the model does not allow a nonzero steady state, even though the oscillations may continue and do not necessarily damp toward zero. This study introduces the driven damped oscillator model which has an additional parameter to identify different patterns of the steady state. Three methods, generalized local linear approximation, continuous time structural equation modeling, and analytic solutions of differential equations are provided to estimate model parameters. A simulation study indicates that parameters in the driven damped oscillator model are well recovered. The model is then illustrated using a data set on the daily reports of sales after a sale promotion. Potential applications and possible expansions of this model are also discussed.     

Detecting Misspecified Multilevel Structural Equation Models with Common Fit Indices: A Monte Carlo Study

This study investigated the sensitivity of common fit indices (i.e., RMSEA, CFI, TLI, SRMR-W, and SRMR-B) for detecting misspecified multilevel SEMs. The design factors for the Monte Carlo study were numbers of groups in between-group models (100, 150, and 300), group size (10, 20, 30, and 60), intra-class correlation (low, medium, and high), and the types of model misspecification (Simple and Complex). The simulation results showed that CFI, TLI, and RMSEA could only identify the misspecification in the within-group model. Additionally, CFI, TLI, and RMSEA were more sensitive to misspecification in pattern coefficients while SRMR-W was more sensitive to misspecification in factor covariance. Moreover, TLI outperformed both CFI and RMSEA in terms of the hit rates of detecting the within-group misspecification in factor covariance. On the other hand, SRMR-B was the only fit index sensitive to misspecification in the between-group model and more sensitive to misspecification in factor covariance than misspecification in pattern coefficients. Finally, we found that the influence of ICC on the performance of targeted fit indices was trivial.     

Interactions between interfacial dislocations and γ/γ′ interface during high temperature – low stress creep in nickel-based single crystal superalloy

ABSTRACT

The interaction between interfacial dislocations and γ/γ′ interface is critical to the high temperature creep properties of single crystal superalloys. However, only a few studies have paid attention to the detailed structure such as local interfacial morphologies and the elemental distribution around interfacial dislocations. In this paper, the interfacial protrusions and related dislocations in a single crystal superalloy after creep at high temperature – low stress have been investigated in detail. It is found that the morphology and size of the interfacial protrusions remain almost the same during the early and middle stages of high temperature creep, which indicates a local equilibrium at the interfacial protrusions. Steps at different height are formed at the γ/γ′ interface at the initial stage of high temperature creep since dislocations could move along the γ/γ′ interface, which indicates that dislocation motion at different creep stage may affect the morphology of γ/γ′ interface.     

Sedimentation of substitutional atoms and phase change in an In-Pb alloy under an ultrastrong gravitational field

It was found that an atomic-scale graded structure was formed, and a phase change occurred, in an In–Pb alloy by the sedimentation of substitutional solute atoms under an ultrastrong gravitational field (820?000?g (maximum); 150°C; 100?h). Continuous gradients in the concentration of Pb (from about 6 to 45?at.%) and In (from about 94 to 55?at.%) and resulting changes in the lattice constant were observed. Fcc (Pb-rich) and tetragonal (In-rich) phases appeared in the strong- and weak-gravity regions respectively from a single starting fct α phase. It is suggested that sedimentation of substitutional atoms can be used to control the compositions and structure of bulk materials and also thin films or layer interfaces.     

Capturing and evaluating blinks from video-based eyetrackers

Blinks are related to several emotional states, and the present report describes a simple, reliable way to measure blinks from the video stream of an eye obtained during eyetracking, where the source of the eye video is a video camera attached to a head-mounted eyetracker. Computer vision techniques are employed to determine the moments that a blink starts and ends, for the purpose of calculating blink frequency and duration. The video is first processed to show blocks of eyelid and pupil movements, and is then analyzed for blink starts and ends. The moment of a blink start is reported when the eyelid starts to move quickly, exceeding a predetermined threshold. The end of a blink arises when the pupil size increases by less than a separate threshold. We observed several different blink patterns from different subjects, and our algorithm was designed to work for all of these patterns. We evaluated our algorithm by manually measuring the true blinks of five different subjects while they were eyetracked. To test the sensitivity and specificity of the algorithm, we employed a series of threshold values to plot the receiver operating characteristic curves. Using the best thresholds, we achieved excellent sensitivity (>90 %) and specificity (>99 %) over the five subjects. Potential applications of this research include real-time, nonintrusive, continuous and automated measurements of mental workload and other emotional states related to blink rates and durations.