Stimulus dependence in probabilistic category learning

• Probabilistic categorization of Visual, Verbal-Auditory and Non-verbal Auditory sets.
• Stimulus presentation was sequential or simultaneous.
• No general performance differences by Modality/Domain.
• Simultaneous Visual leads to better learning than Sequential Visual.
• Early Simultaneous advantage in both Auditory conditions.

The current study investigates whether probabilistic categorization on the Weather Prediction task involves a single, modality/domain general learning mechanism or there are modality/domain differences. The same probabilistic categorization task was used in three modalities/domains and two modes of presentation. Cues consisted of visual, auditory-verbal or auditory-nonverbal stimuli, and were presented either sequentially or simultaneously. Results show that while there was no general difference in performance across modalities/domains, the mode of presentation affected them differently. In the visual modality, simultaneous performance had a general advantage over sequential presentation, while in the auditory conditions, there was an initial advantage of simultaneous presentation, which disappeared, and in the non-verbal condition, gave over to a sequential advantage in the later stages of learning. Data suggest that there are strong peripheral modality effects; however, there are no signs of modality/domain of stimuli centrally affecting categorization.