Yuming Xuan

Image retargeting quality assessment

Content‐aware image retargeting is a technique that can flexibly display images with different aspect ratios and simultaneously preserve salient regions in images. Recently many image retargeting techniques have been proposed. To compare image quality by different retargeting methods fast and reliably, an objective metric simulating the human vision system (HVS) is presented in this paper. Different from traditional objective assessment methods that work in bottom‐up manner (i.e., assembling pixel‐level features in a local‐to‐global way), in this paper we propose to use a reverse order (top‐down manner) that organizes image features from global to local viewpoints, leading to a new objective assessment metric for retargeted images. A scale‐space matching method is designed to facilitate extraction of global geometric structures from retargeted images. By traversing the scale space from coarse to fine levels, local pixel correspondence is also established. The objective assessment metric is then based on both global geometric structures and local pixel correspondence. To evaluate color images, CIE L*a*b* color space is utilized. Experimental results are obtained to measure the performance of objective assessments with the proposed metric. The results show good consistency between the proposed objective metric and subjective assessment by human observers.

Do objects in working memory compete with objects in perception

It is generally assumed that “perceptual object” is the basic unit for processing visual information and that only a small number of objects can be either perceptually selected or encoded in working memory (WM) at one time. This raises the question whether the same resource is used when objects are selected and tracked as when they are held in WM. In two experiments, we measured dual-task interference between a memory task and a Multiple Object Tracking task. The WM tasks involve explicit, implicit, or no spatial processing. Our results suggest there is no resource competition between working memory and perceptual selection except when the WM task requires encoding spatial properties.

Do different emotional valences have same effects on spatial attention

Emotional stimuli have a priority to be processed relative to neutral stimuli. However, it is still unclear whether different emotions have similar or distinct influences on attention. We conducted three experiments to answer the question, which used three emotion valences: positive, negative and neutral. Pictures of money, snake, lamp and letter x were used as stimuli in Experiment 1. In Experiment 2A, schematic emotional faces (angry, smile and neutral face) were used as experimental stimuli to control the stimuli complexity. In Experiment 2B, stimuli were three line drawing pictures selected from the Chinese Version of Abbreviated PAD Emotion Scales, corresponding respectively to anger, joy and neutral emotion. We employed the paradigm of inhibition of return (IOR, an effect on spatial attention that people are slow to react to stimuli which appear at recently attended locations, cf. Posner & Cohen, 1984) which used exogenous cues and included 20% catch trials. Seventy-four university students participated in the experiments. We found that participants needed more time to process negative emotional pictures (Exp1, 2A&2B), and the effect of IOR could happen at the ISI (interstimulus interval) as short as 50ms (Exp1). Meanwhile, the data demonstrated that IOR happened at 50ms ISI only when the schematic face was angry, and RTs of angry schematic faces were significantly longer than RTs of the other two faces (Exp2A). We further found that the expectancy might play a role in explaining these results (Exp3). In all three experiments, we found consistently there was a U-shaped relationship between RT and ISI, irrespective of the cue validity and emotional valence. These results showed that different emotional valences had distinct influences on attention. To be specific positive and neutral emotions could be processed more rapidly than the negative emotion.

What expression could be found more quickly? it depends on facial identities

Visual search task was used to explore the role of facial identity in the processing of facial expression. Participants were asked to search for a happy or sad face in a crowd of emotional face pictures. Expression search was more quickly and accurate when all the faces in a display belonged to one identity than two identities. This suggested the interference of identity variance on expression recognition. At the same time the search speed for a certain expression also depended on the number of facial identities. When faces in a display belonged to one identity, a sad face among happy faces could be found more quickly than a happy face among sad faces; otherwise, when faces in a display belonged to two identities, a happy face could be found more quickly than a sad face.

Automatic and Controlled Processing of Facial Expressions in the Aging Brain

Research on emotional aging has attracted a lot of attention in recent years.However,the field lacks a unified account of the phenomenon.From the perspective of interaction between emotion and cognition,this study intends to investigate effects of automatic and controlled processing of emotional aging.Combining behavioral,ERP and fMRI methods,this study will examine behavioral and neural correlates of these factors,as well as individual differences under these conditions.The research aims to provide empirical data for modeling,and to shed light on the cognitive and neural mechanisms of emotional aging.

The role of emotional scenes in facial expressional recognition: Priming versus contextual effect

Objects were better recognized in consistent scenes (where objects appeared frequently) than inconsistent scenes (where objects appeared rarely). This consistency effect also was found in the facial expressional recognition in scenes. However, the underlying mechanisms of expressional recognition in scenes were not clear. In the present study, we addressed the question of whether emotional scenes influenced recognition of facial expression through top-down priming effect. In two experiments, emotional scenes and facial expressions were presented sequentially or simultaneously and participants were instructed to categorize facial expressions, ignoring scenes. Similar consistency effects and happy face advantage were observed which suggested emotional scenes automatically influenced expressional recognition through priming effect.