Normative measures of verbal material are fundamental in psycholinguistic and cognitive research to control for confounding in experimental procedures and achieve a better comprehension of our conceptual system. Traditionally, normative studies focused on classical psycholinguistic variables, such as concreteness and imageability. Recent works shifted researchers' focus to perceptual strength, in which items are separately rated for each of the five senses. We present a resource including perceptual norms for 1121 Italian words extracted from the Italian version of ANEW. Norms were collected from 57 native-speakers. For each word, participants provided perceptual strength ratings for each of the five perceptual modalities. Perceptual norms performance in predicting human behavior was tested in two novel experiments, a lexical decision and a naming task. Concreteness, imageability and different composite variables representing perceptual strength scores were considered as competing predictors in a series of linear regressions, evaluating the goodness-of-fit of each model. For both tasks, the model with imageability as predictor was found to be the best fitting model according to AIC, while the model with the separately considered five modalities better described data according to the explained variance. These results differ from the ones previously reported for English, in which maximum perceptual strength emerged as the best predictor of behavior. We investigated this discrepancy by comparing Italian and English data on the same set of translated items, thus confirming a genuine cross-linguistic effect. We conclude confirming that perceptual experience influences linguistic processing, even though evaluations from different languages are needed to generalize this claim.

In its strongest formulation, grounded cognition claims that “concepts are made up of sensorimotor information”. Following such equivalence, perceptual properties of objects should consistently influence processing even in purely linguistic tasks, where perceptual information is neither solicited nor required. Previous studies tested this prediction in semantic priming tasks, but they did not observe perceptual influence on participants’ performances. However, those findings suffer from critical shortcomings, which may have prevented potential visually grounded/perceptual effects from being detected. Here, we further investigated this topic by applying an innovative method expected to increase the sensitivity in detecting such perceptual effects. Specifically, we adopted an objective, data-driven computational approach to independently quantify vision-based and language-based similarities for prime-target pairs on a continuous scale. We tested whether these measures predicted behavioral performance in a semantic priming mega-study, with various experimental settings. Vision-based similarity was found to facilitate performances, but a dissociation between vision-based and language-based effects was also observed. Thus, in line with grounded cognition, perceptual properties can facilitate word processing in purely linguistic tasks, but the behavioral dissociation challenges extreme claims of sensorimotor and conceptual equivalence.

Social exclusion, ostracism, and rejection can be emotionally painful because they thwart the need to belong. Building on studies suggesting that the right ventrolateral prefrontal cortex (rVLPFC) is associated with regulation of negative emotions, the present experiment tests the hypothesis that decreasing the cortical excitability of the rVLPFC may increase negative emotional reactions to social exclusion. Specifically, we applied cathodal transcranial direct current stimulation (tDCS) over the rVLPFC and predicted an increment of negative emotional reactions to social exclusion. In Study 1, participants were either socially excluded or included, while cathodal tDCS or sham stimulation was applied over the rVLPFC. Cathodal stimulation of rVLPFC boosted the typical negative emotional reaction caused by social exclusion. No effects emerged from participants in the inclusion condition. To test the specificity of tDCS effects over rVLPFC, in Study 2, participants were socially excluded and received cathodal tDCS or sham stimulation over a control region (i.e., the right posterior parietal cortex). No effects of tDCS stimulation were found. Our results showed that the rVLPFC is specifically involved in emotion regulation and suggest that cathodal stimulation can increase negative emotional responses to social exclusion.

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Transcranial direct current stimulation (tDCS) is increasingly used in both research and therapeutic settings, but its precise mechanisms remain largely unknown. At a neuronal level, tDCS modulates cortical excitability by shifting the resting membrane potential in a polarity-dependent way: anodal stimulation increases the spontaneous firing rate, while cathodal decreases it. However, the neurophysiological underpinnings of anodal/cathodal tDCS seem to be different, as well as their behavioral effect, in particular when high order areas are involved, compared to when motor or sensory brain areas are targeted. Previously, we investigated the effect of anodal tDCS on cortical excitability, by means of a combination of Transcranial Magnetic Stimulation (TMS) and Electroencephalography (EEG). Results showed a diffuse rise of cortical excitability in a bilateral fronto-parietal network. In the present study, we tested, with the same paradigm, the effect of cathodal tDCS. Single pulse TMS was delivered over the left posterior parietal cortex (PPC), before, during, and after 10 min of cathodal or sham tDCS over the right PPC, while recording HD-EEG. Indexes of global and local cortical excitability were obtained both at sensors and cortical sources level. At sensors, global and local mean field power (GMFP and LMFP) were computed for three temporal windows (0–50, 50–100, and 100–150 ms), on all channels (GMFP), and in four different clusters of electrodes (LMFP, left and right, in frontal and parietal regions). After source reconstruction, Significant Current Density was computed at the global level, and for four Broadmann's areas (left/right BA 6 and 7). Both sensors and cortical sources results converge in showing no differences during and after cathodal tDCS compared to pre-stimulation sessions, both at global and local level. The same holds for sham tDCS. These data highlight an asymmetric impact of anodal and cathodal stimulation on cortical excitability, with a diffuse effect of anodal and no effect of cathodal tDCS over the parietal cortex. These results are consistent with the current literature: while anodal-excitatory and cathodal-inhibitory effects are well-established in the sensory and motor domains, both at physiological and behavioral levels, results for cathodal stimulation are more controversial for modulation of exitability of higher order areas.

Due to its safety, portability, and cheapness, transcranial direct current stimulation (tDCS) use largely increased in research and clinical settings. Despite tDCS’s wide application, previous works pointed out inconsistent and low replicable results, sometimes leading to extreme conclusions about tDCS’s ineffectiveness in modulating behavioral performance across cognitive domains. Traditionally, this variability has been linked to significant differences in the stimulation protocols across studies, including stimulation parameters, target regions, and electrodes montage. Here, we reviewed and discussed evidence of heterogeneity emerging at the intra-study level, namely inter-individual differences that may influence the response to tDCS within each study. This source of variability has been largely neglected by literature, being results mainly analyzed at the group level. Previous research, however, highlighted that only a half—or less—of studies’ participants could be classified as responders, being affected by tDCS in the expected direction. Stable and variable inter-individual differences, such as morphological and genetic features vs. hormonal/exogenous substance consumption, partially account for this heterogeneity. Moreover, variability comes from experiments’ contextual elements, such as participants’ engagement/baseline capacity and individual task difficulty. We concluded that increasing knowledge on inter-dividual differences rather than undermining tDCS effectiveness could enhance protocols’ efficiency and reproducibility.

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