Hepatic Portal Venous Gas in a COPD Patient

Although hepatic portal venous gas (HPVG) is usually associated with a grave prognosis, favorable outcomes have been reported in some conditions. A rare case demonstrates the transient occurrence of HPVG in a patient with aerophagia when chronic obstructive pulmonary disease (COPD) occurred, and disappearance after symptoms resolved. The patient's recovery was uneventful and he did not suffer from any abdominal catastrophe. These findings may support the mechanical theory for the occurrence of benign HPVG

Do Fearful Facial Expressions Capture Attention Involuntarily?

It has been claimed that stimuli signaling threat are processed rapidly and draw our attention (e.g., Fox, Russo, & Dutton, 2002). Similarly, it has been argued that expressions of fear have a strong pull on our attention because they signal threat (e.g., Phelps, Ling, & Carrasco, 2006; Vuilleumier & Schwartz, 2001). The present study used a cuing paradigm to examine whether fearful facial expressions capture attention involuntarily (i.e., automatically), even when they are irrelevant. We asked participants to find a letter in a particular color (red or green) and indicate whether it was a “T” or an “L”. Prior to the target display, a cue display was presented. In the face cue condition, one fearful face and one neutral face appeared on opposite sides of the display. In the color cue condition, one green box and one red box appeared on opposite sides of the display (see Figure 1). In both cue conditions, the stimuli (faces and boxes) are irrelevant to the task at hand – identifying letters. Previous cuing studies have concluded that if a participant is looking for a particular color to find the target letter, then other objects in the cue display containing this same color will capture attention. For example, when looking for a red letter, a red box will capture attention. This conclusion is based on the cue validity effect – the finding that response time (RT) is shorter and proportion of error (PE) is smaller when the target appears in the same location as the color cue drawn in the target color than when it appeared in a different location. Stimuli in other colors do not produce a cue validity effect

Elevating Baseline Activation Does Not Facilitate Reading of Unattended Words

Previous studies have disagreed the extent to which people extract meaning from words presented outside the focus of spatial attention. The present study, examined a possible explanation for such discrepancies, inspired by attenuation theory: unattended words can be read more automatically when they have a high baseline level of activation (e.g., due to frequent repetition or due to being expected in a given context). We presented a brief prime word in lowercase, followed by a target word in uppercase. Participants indicated whether the target word belonged to a particular category (e.g., "sport"). When we drew attention to the prime word using a visual cue, the prime produced substantial priming effects on target responses (i.e., faster responses when the prime and target words were identical or from the same category than when they belonged to different categories). When prime words were not attended, however, they produced no priming effects. This finding replicated even when there were only 4 words, each repeated 160 times during the experiment. Even with a very high baseline level of activation, it appears that very little word processing is possible without spatial attention

On the Control of Spatial Attention: Is There an Attentional Bias Toward Threatening Objects?

Stimuli signaling threat are often processed especially rapidly (e.g., Fox, Russo, & Dutton, 2002). Similarly, some studies have suggested that expressions of fear have a strong pull on our attention because they signal threat (e.g., Phelps, Ling, & Carrasco, 2006; Shaw, Lien, Ruthruff, & Allen, in press; Vuilleumier & Schwartz, 2001). These stimuli, however, were typically relevant to the task (i.e., were targets). The present study questioned whether fearful facial expressions capture attention involuntarily (i.e., automatically) even when they are irrelevant. A cuing paradigm was used in the present study. Participants were instructed to search the target display for a pre-specified target object, which was either a letter in a specific color (Exp. 1) or a face with a specific emotional expression (Exps. 1-5). The target display was always preceded by a non-informative cue display, which could contain a fearful face and/or a neutral face. The face could appear in the same location as the upcoming target (“valid” trials; 25% of the trials) or in a different location (“invalid” trials; 75% of the trials). The critical measure of attentional capture is the cue validity effect (Invalid minus valid) on response time (RT) and Proportion error (PE)

Without words for emotions: Is the emotional processing deficit in alexithymia caused by dissociation or suppression?

Alexithymia is a trait where individuals have difficulty identifying feeling and finding a word to express emotion. Some studies have suggested that this deficit is due to dissociation (repression), or an inability to perceive emotions, whereas others argued that the deficit is due to suppression of emotional information after it has already been perceived. This study used both behavioral measures (response time) and electrophysiological measures (brain activity) to test these two hypotheses. Both Alexithymia group and non-Alexithymia control group were selected based on their scores on the Toronto Alexithymia Scale (TAS-20). They were asked to search for either fearful or happy faces and determined the color of the box containing the target face. We measured the N2pc effect (an index of attention allocation) and the Pd effect (an index of suppression). In supporting the suppression hypothesis proposed by our earlier study, we expect that the Alexithymia group would produce similar N2pc effects as the control group but exhibit a larger Pd effect than the control group

An Electrophysiological Dual-Task Study of Visual Word Processing without Task Switching

A previous dual-task study (Lien, Ruthruff, Cornett, Goodin, & Allen, 2008) provided evidence that people have difficulty identifying words while central attention is devoted to another non-word task. In that study, participants performed an auditory Task 1 regarding tone pitch and a visual word Task 2. However, it’s possible that the real obstacle to word identification was not the lack of central attention, but rather the required task switch. The present study therefore examined this issue by using a dual-task paradigm in which participants performed essentially the same word task for both Task 1 and Task 2 (i.e., there was no task switch). We measured the N400 effect elicited by Task-2 word, a measure of whether participants detected a mismatch between the word and the current semantic context. The N400 effect can occur only if a word has been identified. We found that the N400 effect was strongly attenuated for Task-2 words presented nearly simultaneously with Task-1 words. This finding suggests that, even without task switching, words still cannot be identified without central attentional resources.Keywords: Attention, Word Processing, Dual Tas

Attention Capture While Switching Search Strategies: Evidence for a Breakdown in Top-Down Attentional Control

Whereas capture experiments typically repeat a single task many times, real world cognition is characterized by frequent switching. Lien, Ruthruff, and Johnston (2010) reported that the attentional control system can rapidly and fully switch between different search settings (e.g., red to green), with no carryover and no inter-trial priming. The present study examined whether this impressive flexibility is possible even when the switch is not between different features along the same dimension, but between mutually incompatible search modes. On each trial, participants were prompted to find and identify the letter that was in a specific color (feature search mode) or was uniquely colored (singleton search mode). Within each block, search mode was either pure or mixed; the mixed blocks contained a fixed AABB search sequence (singleton-singleton-feature- feature) in Experiment 1 and a random sequence in Experiment 2. The target display was preceded by a non-informative cue display containing a non-target color singleton. In pure feature search blocks, these irrelevant singleton cues were generally unable to capture attention, replicating previous findings of “contingent capture.” In mixed blocks, however, irrelevant color singletons captured attention on feature search trials. This breakdown indicates a limitation in the sharpness of attentional control following mode switches, which might be common in the real world.Keywords: Cognitive Control and Switching, Visual Search Strategy, Attention CaptureKeywords: Cognitive Control and Switching, Visual Search Strategy, Attention Captur

Visual Attention and Working Memory: Are Low Memory Capacity Individuals More Easily Distracted?

Visual working memory (VWM) allows us temporarily hold images in our minds and manipulate them. As an example, you can remember a face you just saw, or try to imagine how a room would look with a different arrangement of furniture. Previous studies have shown that individuals with low VWM capacity (able to remember only a few visual items) are much more susceptible to distraction than high VWM individuals (e.g., Poole & Kane, 2009). Nevertheless, it is unclear whether their inability to avoid distraction occurs because their spatial attention is easily captured by distractions (the capture hypothesis) or because they have difficulty disengaging attention from distractions (the disengagement hypothesis). The present study tested between these two hypotheses

An Electrophysiological Study of Attention Capture by Salience: Does Rarity Enable Capture?

Several behavioral studies have suggested that rarity is critical for enabling irrelevant, salient objects to capture attention. We tested this hypothesis using the N2pc, thought to reflect attentional allocation. A cue display was followed by a target display in which participants identified the letter in a specific color. Experiment 1 pitted rare, irrelevant abrupt onset cues (appearing on only 20% of trials) against target-relevant color cues. The relevant color cue produced large N2pc and cue validity effects, even when competing with a rare, salient, simultaneous abrupt onset. Similar results occurred even when abrupt onset frequency was reduced to only 10% of trials (Experiment 2). Experiment 3 examined rare, irrelevant color singleton cues (20% of trials). Despite being rare and salient, these singleton cues produced no N2pc or cue validity effect, indicating little attentional capture. Experiment 4 greatly increased color cue salience by adding 4 background boxes, increasing color contrast, and tripling the cue display duration (from 50 to 150 ms). Small cue validity and N2pc effects were obtained, but did not strongly depend on degree of rarity (20% vs. 100%). We argue that rarity by itself is neither necessary nor sufficient to produce attention capture.Keywords: Visual attention, N2pc, Attention captureKeywords: Visual attention, N2pc, Attention captur