What's the meaning of this? A behavioral and neurophysiological investigation into the principles behind the classification of visual emotional stimuli.
Two experiments were performed to investigate the principles by which emotional stimuli are classified on the dimensions of valence and arousal. In Experiment 1, a large sample of healthy participants rated emotional stimuli according to both broad dimensions. Hierarchical cluster analyses performed on these ratings revealed that stimuli were clustered according to their semantic content at the beginning of the agglomerative process. Example semantic themes include food, violence, nudes, death, and objects. Importantly, this pattern occurred in a parallel fashion for ratings on both dimensions. In Experiment 2, we investigated if the same semantic clusters were differentiated at the neurophysiological level. Intracerebral EEG was recorded from 18 patients with intractable epilepsy who viewed the same set of stimuli. Not only did electrocortical responses differentiate between these data-defined semantic clusters, they converged with the behavioral measurements to highlight the importance of categories associated with survival and reproduction. These findings provide strong evidence that the semantic content of affective material influences their classification along the broad dimensions of valence and arousal, and this principle of categorization exerts an effect on the evoked emotional response. Future studies should consider data-driven techniques rather than normative ratings to identify more specific, semantically related emotional images.
Behavioural and Social Neuroscience Research Group, CEITEC - Central European Institute of Technology, Masaryk University, Brno, Czech Republic.
Kristína
0000-0001-9198-1083
K
Czekóová
Behavioural and Social Neuroscience Research Group, CEITEC - Central European Institute of Technology, Masaryk University, Brno, Czech Republic.
Daniel J
DJ
Shaw
Institute of Psychology, Academy of Sciences of the Czech Republic, Brno, Czech Republic.
Tomáš
T
Urbánek
Institute of Scientific Instruments, Academy of Sciences of the Czech Republic, Brno, Czech Republic.
Jan
J
Chládek
Multimodal and Functional Imaging Laboratory, CEITEC - Central European Institute of Technology, Masaryk University, Brno, Czech Republic.
Martin
M
Lamoš
Behavioural and Social Neuroscience Research Group, CEITEC - Central European Institute of Technology, Masaryk University, Brno, Czech Republic.
Robert
R
Roman
Behavioural and Social Neuroscience Research Group, CEITEC - Central European Institute of Technology, Masaryk University, Brno, Czech Republic.|Brno Epilepsy Centre, Department of Neurology, St. Anne's University Hospital and Medical Faculty of Masaryk University, Brno, Czech Republic.
Milan
M
Brázdil
D000328:Adult; D000339:Affect / Q000502:physiology; D001143:Arousal; D002540:Cerebral Cortex / Q000502:physiology*; D016000:Cluster Analysis; D004569:Electroencephalography; D004644:Emotions / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D012660:Semantics; D014796:Visual Perception / Q000502:physiology*; D055815:Young Adult
Categorization; Cluster analysis; Emotion; Intracerebral EEG; Semantic content