Association Between Preoperative Mechanical Bowel Preparation and Postoperative Cognitive Dysfunction in Patients Undergoing Colorectal Surgery: A Pilot Randomized Controlled Trial.

The effect is considered a classic in psycholinguistic literature, a marked exception to the longstanding view that the link between the phonetic form of words and their referents is arbitrary (). Across cultures, languages, and development, humans are found to share the tendency to associate non-words like and with round shapes and and with angular shapes (); this finding was recently replicated in a large online study with adult speakers of 25 languages (in nine language families and 10 writing systems; ). Multiple theories have sought to provide a mechanistic explanation of this phenomenon. First, it might reflect links between the rounded or angular visual appearance of the objects, and the open/rounded versus wide/narrowed appearance of a speaker’s lips when pronouncing the verbal labels (); this explanation was dubbed the “mouth-shape hypothesis” by . Listeners may also associate round and angular objects with acoustic or phonological features of consonant and vowel sounds (; ; ; ); see discussion in . For literate individuals, orthography (i.e., letter curvature) may also play a role in word-shape associations (; ). An alternative explanation attributes these effects to cross-modal correspondences between the physical and acoustic properties of objects and how they move in the world. That is, due to the physics of sound transmission, rounded objects such as bowling balls and apples make continuous noises of lower spectral frequency (e.g., dull thudding noises); spiky objects such as forks and model airplanes make more spectrally distinct, discontinuous noises (). A series of experiments () strongly supports the latter, general, explanation, finding that it is the “timbre” (tonal quality of a sound) associated with an object that elicits the Bouba-Kiki effect. Additional work provides evidence of sound-action links, such that specific motor actions (such as forward versus backward hand motions) are tied to specific speech sounds (). The evidence of behavioral links among sounds, visual qualities, and motor actions in behavior is likely grounded in the neural processes underlying perception and action. Specifically, cortical regions dedicated to processing visual inputs (how images look), auditory inputs (how words sound), and motor actions (how we engage in physical actions with objects) are tightly linked via neural circuits. The complex process of multisensory integration – the ability to integrate specific pieces of sensory information derived from distinct sensory systems into a coherent source, merged into a unified percept – undergoes tremendous developmental change (). This integration initially relies more on low-level aspects of the stimuli, but shifts to a reliance on experiential features over developmental time. The process of binding together temporally synchronous sensory and motor cues is foundational to development. For example, as discussed by Wallace and colleagues, early attention to visual cues associated with the spoken speech signal (e.g., facial movements) is linked to early speech perception, vocal development, and language acquisition ().