Multimodal integration in the chicken.

In everyday life we constantly perceive and discriminate between a large variety of sensory inputs, the vast majority of which consist of more than one modality. We performed two experiments to investigate whether chickens use the information present in multimodal signals. To test whether audiovisual stimuli are better detected than visual or acoustic stimuli alone, we first measured the detection threshold with a staircase paradigm. We found that chickens were able to detect weaker stimuli using audiovisual stimuli. Next, we tested whether the multimodal nature of a stimulus also increases the discrimination between two stimuli by measuring the smallest difference that the animals could still distinguish from each other. We found that chickens can discriminate smaller differences using audiovisual stimuli in comparison to visual stimuli alone, but not in comparison to acoustic stimuli alone. Thus, even in a relatively unspecialized species such as the chicken, the benefits of multimodal integration are exploited for sensory processing.