1. Do different measures of similarity vary in predicting semantic priming?
We carried out behavioural experiments to test whether relatedness by verbal features, co-occurrence or word association predicts semantic priming (faster responses to target word after a related one), selecting word pairs related only by one measure. Priming occurred only for pairs related by association, indicating importance of this measure for theories of semantic representation.
2. Does featural similarity affect pupil responses in false memory and recognition for words?
We measured pupil dilation in an old/new recognition task, controlling for word association and co-occurrence to allow us to specifically investigate featural similarity. New words in the recognition test with high similarity to studied words tended to be mistakenly identified as old, and had more pupil dilation than those with low similarity, suggesting that featural similarity is relevant, beyond association and co-occurrence, for semantic representation.
3. How independent are different measures of similarity?
The studies above show that these measures can predict behavioural effects. To test their joint contribution in reflecting semantic representations, we compared similarity measures between all pairs of words, including new association and co-occurrence norms we collected. We found high similarity between representations: despite some degree of independence in predicting behavioural effects, these measures might reflect a common underlying semantic system.
To test this question more directly we compared an even wider variety of relatedness measures. Consistent with the previous study, very different data sources are employed similarly in semantic representations and surprisingly, they reflect a gradient of depth of information encoding.
4. Does similarity in brain activity correlate with similarity derived from different measures?
We used functional magnetic resonance imaging (fMRI) and functional near-infrared spectroscopy (fNIRS) in two experiments to test this question. Preliminary analyses show differences in how the left-lateralized semantic network responds to different similarity measures, varying as a function of concreteness, consistent with the idea that different organisational principles govern representations of abstract and concrete words.
5. Is processing of semantic dimensions affected by divided attention?
In a behavioural study using a feature selection task, we tested effects of featural relevance on semantic performance under conditions of divided attention. As the relevance of the distracter feature increased, there was greater dual-task disruption, indicating that semantic relevance is an organizing principle of semantic representation, and that domain-general control processes are more relevant to the capacity to efficiently avoid distracting information during semantic decision-making.
6. Do participant-level variables modulate semantic and conceptual processing?
We tested the extent to which grammatical gender in Italian and German affected speakers' affective ratings (valence, arousal and dominance), and whether this might be affected by individual variation in sex and age. We found that grammatical gender did not affect affective ratings within or across languages, nor were there any interactions with speakers’ age and sex. These findings suggest that grammatical gender does not primarily affect conceptual representations, at least where affect is concerned.
We carried out the following dissemination activities so far:
- Two empirical papers published in international peer-reviewed journals, and one as a conference proceeding. Eight more papers arising from the project are in preparation or under revision for publication.
- Several presentations at international conferences and workshops targeting experts in language, semantic and conceptual processing.
- Public engagement: promotion of women's participation in science; online activity bringing together researchers and school students; European Researcher's night to share news about research in neuroscience to members of the public.
