Temporal brain dynamics of the competition between proximity and shape similarity grouping cues in vision.

Perceptual grouping operations are crucial for visual object recognition. From the pioneering proposal of Gestalt psychologists, research has focused mostly on the dynamics of single grouping laws. However, the integration between grouping cues has received relatively less attention. The present event-related potentials (ERPs) study aimed to examine the brain correlates of the competition between multiple grouping cues (namely, shape similarity versus proximity) in visual patterns by means of a selective attention paradigm that allows to measure the contribution of each cue independently to the competition between them. Behavioural results indicated larger interference effects of shape similarity on proximity cues when both cues compete. ERPs data showed two main neural effects. First, the amplitude of a negative component peaking around 250 ms (N200) was modulated by the interaction between proximity and shape similarity cues. Specifically, the single shape similarity relative to competing shape similarity cues elicited enhanced amplitudes. This finding seems to reflect the visual salience and/or the processing fluency of the shape similarity grouping factor. Remarkably, it can be considered an indirect brain signature of the competitive interaction between grouping cues. Second, we found larger P300 amplitudes elicited by single displays compared with competing trials, as well as by proximity relative to shape similarity cues, which presumably reflects higher perceived confidence in decisions during the processes joining perception to action.

Recognition memory advantage for negative emotional words has an early expiry date: Evidence from brain oscillations and ERPs.

Evidence from prior studies has shown an advantage in recognition memory for emotional compared to neutral words. Whether this advantage is short-lived or rather extends over longer periods, as well as whether the effect depends on words' valence (i.e., positive or negative), remains unknown. In the present ERP/EEG study, we investigated this issue by manipulating the lag distance (LAG-2, LAG-8 and LAG-16) between the presentation of old and new words in an online recognition memory task. LAG differences were observed at behavior, ERPs and in the theta frequency band. In line with previous studies, negative words were associated with faster reaction times, higher hit rates and increased amplitude in a positive ERP component between 386 and 564 ms compared to positive and neutral words. Remarkably, the interaction of LAG by EMOTION revealed that negative words were associated with better performance and larger ERPs amplitudes only at LAG-2. Also in the LAG-2 condition, emotional words (i.e., positive and negative words) induced a stronger desynchronization in the beta band between 386 and 542 ms compared to neutral words. These early enhanced memory effects for emotional words are discussed in terms of the Negative Emotional Valence Enhances Recapitulation (NEVER) model and the mobilization-minimization hypothesis.

Negative induced mood influences word production: An event-related potentials study with a covert picture naming task.

The present event-related potentials (ERPs) study investigated the effects of mood on phonological encoding processes involved in word generation. For this purpose, negative, positive and neutral affective states were induced in participants during three different recording sessions using short film clips. After the mood induction procedure, participants performed a covert picture naming task in which they searched letters. The negative compared to the neutral mood condition elicited more negative amplitudes in a component peaking around 290ms. Furthermore, results from source localization analyses suggested that this activity was potentially generated in the left prefrontal cortex. In contrast, no differences were found in the comparison between positive and neutral moods. Overall, current data suggest that processes involved in the retrieval of phonological information during speech generation are impaired when participants are in a negative mood. The mechanisms underlying these effects were discussed in relation to linguistic and attentional processes, as well as in terms of the use of heuristics.