Melissa L.-H. Võ

The Berlin Affective Word List Reloaded (BAWL-R).

The study presented here provides researchers with a revised list of affective German words, the Berlin Affective Word List Reloaded (BAWL-R). This work is an extension of the previously published BAWL (Võ, Jacobs, & Conrad, 2006), which has enabled researchers to investigate affective word processing with highly controlled stimulus material. The lack of arousal ratings, however, necessitated a revised version of the BAWL. We therefore present the BAWL-R, which is the first list that not only contains a large set of psycholinguistic indexes known to influence word processing, but also features ratings regarding emotional arousal, in addition to emotional valence and imageability. The BAWL-R is intended to help researchers create stimulus material for a wide range of experiments dealing with the affective processing of German verbal material.

Incidental effects of emotional valence in single word processing: An fMRI study

The present study aimed at identifying the neural responses associated with the incidental processing of the emotional valence of single words using event-related functional magnetic resonance imaging (fMRI). Twenty right-handed participants performed a visual lexical decision task, discriminating between nouns and orthographically and phonologically legal nonwords. Positive, neutral and negative word categories were matched for frequency, number and frequency of orthographic neighbors, number of letters and imageability. Response times and accuracy data differed significantly between positive and neutral, and positive and negative words respectively, thus, replicating the findings of a pilot study. Words showed distributed, mainly left hemisphere activations, indicating involvement of a neural network responsible for semantic word knowledge. The neuroimaging data further revealed areas in left orbitofrontal gyrus and bilateral inferior frontal gyrus with greater activation to emotional than to neutral words. These brain regions are known to be involved in processing semantic and emotional information. Furthermore, distinct activations associated with positive words were observed in bilateral middle temporal and superior frontal gyrus, known to support semantic retrieval, and a distributed network, namely anterior and posterior cingulate gyrus, lingual gyrus and hippocampus when comparing positive and negative words. The latter areas were previously associated with explicit and not incidental processing of the emotional meaning of words and emotional memory retrieval. Thus, the results are discussed in relation to models of processing semantic and episodic emotional information.

The Invisible Gorilla Strikes Again: Sustained Inattentional Blindness in Expert Observers

Researchers have shown that people often miss the occurrence of an unexpected yet salient event if they are engaged in a different task, a phenomenon known as inattentional blindness. However, demonstrations of inattentional blindness have typically involved naive observers engaged in an unfamiliar task. What about expert searchers who have spent years honing their ability to detect small abnormalities in specific types of images? We asked 24 radiologists to perform a familiar lung-nodule detection task. A gorilla, 48 times the size of the average nodule, was inserted in the last case that was presented. Eighty-three percent of the radiologists did not see the gorilla. Eye tracking revealed that the majority of those who missed the gorilla looked directly at its location. Thus, even expert searchers, operating in their domain of expertise, are vulnerable to inattentional blindness.

Affective processing within 1/10th of a second: High arousal is necessary for early facilitative processing of negative but not positive words

Lexical decisions to high- and low-arousal negative words and to low-arousal neutral and positive words were examined in an event-related potentials (ERP) study. Reaction times to positive and high-arousal negative words were shorter than those to neutral (low-arousal) words, whereas those to low-arousal negative words were longer. A similar pattern was observed in an early time window of the ERP response: Both positive and high-arousal negative words elicited greater negative potentials in a time frame of 80 to 120 msec after stimulus onset. This result suggests that arousal has a differential impact on early lexical processing of positive and negative words. Source localization in the relevant time frame revealed that the arousal effect in negative words is likely to be localized in a left occipito-temporal region including the middle temporal and fusiform gyri. The ERP arousal effect appears to result from early lexico-semantic processing in high-arousal negative words.

Cross-validating the Berlin Affective Word List.

We introduce the Berlin Affective Word List (BAWL) in order to provide researchers with a German database containing both emotional valence and imageability ratings for more than 2,200 German words. The BAWL was cross-validated using a forced choice valence decision task in which two distinct valence categories (negative or positive) had to be assigned to a highly controlled selection of 360 words according to varying emotional content (negative, neutral, or positive). The reaction time (RT) results corroborated the valence categories: Words that had been rated as “neutral” in the norms yielded maximum RTs. The BAWL is intended to help researchers create stimulus materials for a wide range of experiments dealing with the emotional processing of words.

Does gravity matter? Effects of semantic and syntactic inconsistencies on the allocation of attention during scene perception.

It has been shown that attention and eye movements during scene perception are preferentially allocated to semantically inconsistent objects compared to their consistent controls. However, there has been a dispute over how early during scene viewing such inconsistencies are detected. In the study presented here, we introduced syntactic object-scene inconsistencies (i.e., floating objects) in addition to semantic inconsistencies to investigate the degree to which they attract attention during scene viewing. In Experiment 1 participants viewed scenes in preparation for a subsequent memory task, while in Experiment 2 participants were instructed to search for target objects. In neither experiment were we able to find evidence for extrafoveal detection of either type of inconsistency. However, upon fixation both semantically and syntactically inconsistent objects led to increased object processing as seen in elevated gaze durations and number of fixations. Interestingly, the semantic inconsistency effect was diminished for floating objects, which suggests an interaction of semantic and syntactic scene processing. This study is the first to provide evidence for the influence of syntactic in addition to semantic object-scene inconsistencies on eye movement behavior during real-world scene viewing.

The time course of initial scene processing for eye movement guidance in natural scene search

A brief glimpse of a scene is sufficient to comprehend its gist. Does information available from a brief glimpse also support further scene exploration? In five experiments, we investigated the role of initial scene processing on eye movement guidance for visual search in scenes. We used the flash-preview moving-window paradigm to separate the duration of the initial scene glimpse from subsequent search. By varying scene preview durations, we found that a 75-ms preview was sufficient to lead to increased search benefits compared to a no-preview control. Search efficiency was further increased by inserting additional scene-target integration time before search initiation: Reducing preview durations to as little as 50 ms led to search benefits only when combined with prolonged integration time. We therefore propose that both initial scene presentation duration and scene-target integration time are crucial for establishing contextual guidance in complex, naturalistic scenes. The present findings show that fast scene processing is not limited to activating gist. Instead, scene representations generated from a brief scene glimpse can also provide sufficient information to guide gaze during object search as long as enough time is available to integrate the initial scene representation.

Welcome to the real world: Validating fixation-related brain potentials for ecologically valid settings

Exploration of the real world usually expresses itself through a perceptual behaviour that is complex and adaptive -- an interplay between external visual and internal cognitive states. However, up to now, the measurement of electrophysiological correlates of cognitive processes has been limited to situations, in which the experimental setting confined visual exploration to the mere reception of a strict serial order of events. Here we show -- exemplified by the well known old/new effect in the domain of visual word recognition -- that an alternative approach that utilizes brain potentials corresponding to eye fixations during free exploration reveals effects as reliable as conventional event-related brain potentials.

Differential Electrophysiological Signatures of Semantic and Syntactic Scene Processing

In sentence processing, semantic and syntactic violations elicit differential brain responses observable in event-related potentials: An N400 signals semantic violations, whereas a P600 marks inconsistent syntactic structure. Does the brain register similar distinctions in scene perception? To address this question, we presented participants with semantic inconsistencies, in which an object was incongruent with a scene’s meaning, and syntactic inconsistencies, in which an object violated structural rules. We found a clear dissociation between semantic and syntactic processing: Semantic inconsistencies produced negative deflections in the N300-N400 time window, whereas mild syntactic inconsistencies elicited a late positivity resembling the P600 found for syntactic inconsistencies in sentence processing. Extreme syntactic violations, such as a hovering beer bottle defying gravity, were associated with earlier perceptual processing difficulties reflected in the N300 response, but failed to produce a P600 effect. We therefore conclude that different neural populations are active during semantic and syntactic processing of scenes, and that syntactically impossible object placements are processed in a categorically different manner than are syntactically resolvable object misplacements.

When Does Repeated Search in Scenes Involve Memory? Looking At Versus Looking For Objects in Scenes

One might assume that familiarity with a scene or previous encounters with objects embedded in a scene would benefit subsequent search for those items. However, in a series of experiments we show that this is not the case: When participants were asked to subsequently search for multiple objects in the same scene, search performance remained essentially unchanged over the course of searches despite increasing scene familiarity. Similarly, looking at target objects during previews, which included letter search, 30 seconds of free viewing, or even 30 seconds of memorizing a scene, also did not benefit search for the same objects later on. However, when the same object was searched for again memory for the previous search was capable of producing very substantial speeding of search despite many different intervening searches. This was especially the case when the previous search engagement had been active rather than supported by a cue. While these search benefits speak to the strength of memory-guided search when the same search target is repeated, the lack of memory guidance during initial object searches-despite previous encounters with the target objects-demonstrates the dominance of guidance by generic scene knowledge in real-world search.