Amodal Perception

Amodal (meaning “without” modality) perception is perception of information that is common or redundant across multiple senses (e.g., auditory, visual, tactile). Amodal information includes changes along three basic parameters of stimulation—time, space, and intensity. Properties of objects and events such as temporal synchrony, rhythm, tempo, duration, intensity, and co-location are common across auditory, visual, and proprioceptive stimulation. Properties [Page 45]such as shape, substance, and texture are common across visual and tactile stimulation. For example, the same rhythm and tempo can be detected by seeing or hearing the pianist strike the notes of the keyboard, and the same size, shape, and texture can be detected by seeing or feeling an apple.

Virtually all events occur across time, are distributed across space, and have a characteristic intensity pattern, so virtually all events provide amodal information. For example, speech comprises changes in audiovisual synchrony, tempo, rhythm, and intonation (intensity changes) that are common to the movements of the face and the sounds of the voice. Self-motion produces proprioceptive feedback (information from the muscles, joints, and vestibular system) that is synchronized and shares temporal and intensity changes with the sight of self-motion (e.g., seeing and feeling one's hand move). Perceiving amodal information is critically important for organizing early perceptual and cognitive development and for accurate perception of everyday events in children and adults alike.

The term amodal has also been used in a different sense—to refer to perception in the absence of direct information from a specific sense modality. For example, in visual perception, amodal completion describes how we perceive a unitary shape (e.g., a ball), even when part of the object or shape is occluded (hidden) behind another object (e.g., a block). Even infants can accurately perceive a partially hidden shape if the occluder is moved back and forth, progressively revealing and then hiding the object's contours. Scientists propose that we perceive unitary shape by detecting visual invariants (patterns that remain constant across change) through object motion, whereas others maintain that we must fill in the missing information by inference or cognitive processes. Whatever the process, the term amodal referring to incomplete information is not consistent with the previous definition (which refers to information that is fully available and can be directly perceived through more than one sense) and, thus, will not be discussed further. This entry describes the history, theory, and development of amodal perception.