Touch Cannot Attentionally Select Signals Based on Feature Binding

For human sensory processing, cluttered real-world environments where signals from multiple objects or events overlap are challenging. A cognitive function useful in such situations is an attentional selection of one signal from others based on the difference in bound feature. For instance, one can visually select a specific orientation if it is uniquely colored. However, here we show that unlike vision, touch is very poor at feature-based signal selection. We presented two-orthogonal line segments with different vibration textures to a fingertip. Though observers were markedly sensitive to each feature, they were generally unable to identify the orientation bound with a specific texture when the segments were presented simultaneously or in rapid alternation. A similar failure was observed for a direction judgment task. These results demonstrate a general cognitive limitation of touch, highlighting its unique bias to integrate multiple signals into a global event rather than segment them into separate events.