Pitch–Luminance Crossmodal Correspondence in the Baby Chick: An Investigation on Predisposed and Learned Processes

Abstract

Our senses are constantly reached by a multitude of stimuli from all different sensory modalities. To create a coherent representation of the environment, we must integrate the various unimodal inputs that refer to the same object into a single multimodal representation. In some cases, however, we tend to bind certain properties of the stimuli without any apparent reason, which is a phenomenon named crossmodal correspondence. For instance, we match a spiky or a rounded shape with the sound “Kiki” or “Bouba”, respectively. Similarly, we associate the left hemispace with low luminance and the right one with high luminance. Instances of crossmodal correspondences were described also in other mammals, and recently, a case of space-luminance crossmodal correspondence was reported in birds (i.e., domestic chicks). Here, we investigate the presence of pitch–luminance crossmodal correspondence in three-day-old chicks, employing experimental methods that exploit either predisposed or learned processes. While failing to report evidence for this phenomenon, we discuss the difference between statistical and structural crossmodal correspondences and the possible role of environmental factors in determining their emergence. Moreover, we discuss the importance of the different experimental methodologies to investigate distinct aspects of this perceptual phenomenon to reach a deeper understanding and unveil the role of innate vs. learned mechanisms.

Humans (Homo sapiens) but not baboons (Papio papio) demonstrate crossmodal pitch‐luminance correspondence

“…Our results are consistent with previous results showing no evidence of structural crossmodal mappings in nonhuman primates (Margiotoudi et al, 2019(Margiotoudi et al, , 2022 or in other animals such as chicks (Loconsole et al, 2022). This could suggest that some crossmodal correspondences might not be shared with other nonhuman species, thus reopening the possibility that those mappings, and in particular the pitch-luminance mapping, could be mediated by language, in English the same adjectives to refer to luminance and pitch, namely "high" and "low."…”

“…Another study shows that chicks prefer to associate stimuli situated at their right with brighter stimuli (a space-luminance mapping; Loconsole et al, 2021). Lastly, the pitch-luminance mapping-where higher pitch is associated with bright stimuli and lower pitch to dark stimuli-has been found in chimpanzees (Ludwig et al, 2011), but not in chicks (Loconsole et al, 2022). Collectively, these results suggest that certain cross-modal correspondences have nonlinguistic origins.…”

“…Two studies provide evidence that domestic dogs prefer to associate higher frequencies with high spatial positions (a pitch‐elevation mapping; Korzeniowska et al, 2019) and with larger stimuli (a pitch‐size mapping, Korzeniowska et al, 2022), Another study shows that chicks prefer to associate stimuli situated at their right with brighter stimuli (a space‐luminance mapping; Loconsole et al, 2021). Lastly, the pitch‐luminance mapping–where higher pitch is associated with bright stimuli and lower pitch to dark stimuli– has been found in chimpanzees (Ludwig et al, 2011), but not in chicks (Loconsole et al, 2022). Collectively, these results suggest that certain cross‐modal correspondences have nonlinguistic origins.…”

Exploring Group Differences in the Crossmodal Correspondences

“…One might have expected that any putatively structural correspondences, such as between auditory loudness and visual brightness, would emerge prior to more arbitrary and artificial statistical correspondences (cf. Loconsole et al, 2022;Walker-Andrews, 1994). According to Marks et al (1987), certain cross-modal correspondences likely strengthen with age.…”

Pitch-size crossmodal correspondence in tortoises (Testudo hermanni)

“…In particular, instances of spontaneous crossmodal associations have been recently identified at the onset of life, in chicks tested soon after hatching, suggesting that the brain may be spontaneously organised to allow crossmodal predictions/associations [24]. It is yet to be determined to what extent relevant experiences play a role in determining the emergence of certain associations [25].…”