Musicians appear less prone to the ventriloquism effect than non-musicians, new research led by Matthew Paul O’Donohue at the Queensland University of Technology suggests. The study compared 35 musicians with 35 non-musicians to explore why the illusion occurs, with findings published in the Journal of Experimental Psychology: Human Perception and Performance.
The ventriloquism effect is a multisensory illusion in which a sound is perceived as originating from a nearby visual stimulus rather than from its true source. The brain typically fuses information from different senses and tends to lean on vision when localisation is involved.
Musical training is thought to sharpen the brain’s integration of sights and sounds, and prior work by the same team showed musicians outperform non-musicians at detecting mismatches between auditory and visual events. Two earlier experiments by the researchers also found that musicians exhibited less ventriloquism when tasked with locating only the sound.
To understand the cause of the difference, the authors proposed two possible explanations: that musicians perceive sounds or sights more precisely, or that they hold a weaker built-in expectation that a sound and a visual flash come from the same source. Based on their earlier work, they predicted the latter would hold.
The study involved 35 musicians and 35 nonmusicians, most of whom were first‑year psychology students. Musicians averaged 22 years of age, nonmusicians 20, and each group included 26 women. Musicians were defined as having at least seven years of instrument experience and playing for about an hour per week on average over the past year; on average, they had played their main instrument for around 12 years. Nonmusicians had no more than 12 months of instrument experience outside school and no more than two years of compulsory school music lessons.
Participants sat in a dark room facing a screen that concealed five speakers. On each trial, a brief flash, a burst of noise, or both appeared from one of five positions along a horizontal line, and participants used a mouse to indicate where each stimulus came from. When both stimuli appeared together, participants located each one separately, dividing attention between hearing and sight. On combined trials, the flash and sound originated from the same position only 20 per cent of the time.
The full set of 420 trials was completed twice by each participant. Before the second run, participants were told that the flash and the sound would come from the same location only 20 per cent of the time, and this information was reminded at the start of each block. The researchers used this manipulation to test whether simple instructions could alter expectations and whether musicians’ advantage depended on assumptions formed during the experiment.
When only one stimulus was presented, musicians and nonmusicians were equally precise at locating the flash or the sound. For both groups, localisation accuracy for flashes declined as they moved away from straight ahead.
On trials with both stimuli, musicians’ judgments of the sound were pulled toward the flash about 1.6 degrees less than those of nonmusicians, on average. The effect was modest and survived in one of two statistical analyses but not the other. After participants learned the 20 per cent contingency, the ventriloquism effect diminished overall, but musicians still showed less of it than nonmusicians.
The researchers interpreted the pattern through a mathematical model of how the brain decides whether to combine information from sight and sound. The model attributed the group difference to musicians’ lower prior expectation that sound and flash share a common source, rather than to differences in sensory precision. The instruction to adjust expectations lowered this prior across participants, but nearly all participants who began with an expectation below 20 per cent raised it, indicating that people adjust their priors to align with the information provided.
“Our results suggest that musicians tend to exhibit less spatial ventriloquism than nonmusicians even when distributing their attention across audition and vision. … Finally, we have shown that this prior expectation changes when participants are informed of the true probability of a common location for the stimuli, demonstrating that top–down factors can exert a strong influence on this Bayesian prior,” the study authors concluded.
While the study enhances understanding of the ventriloquism effect, it cannot prove that musical training itself causes reduced illusion. The researchers compared existing musicians with nonmusicians rather than randomly assigning people to learn an instrument, so other traits may contribute to the observed difference. The authors note that musicians in the sample played a range of instruments, and subgroups such as orchestral players might display stronger auditory spatial skills or integrate visual cues differently. It remains unclear whether the instructional manipulation altered perception or merely the participants’ responses.
The paper, A Multisensory Causal Inference Prior is Attenuated in Musicians and is Further Attenuated Following Instruction, was authored by Matthew Paul O’Donohue, Naohide Yamamoto, Brian Odegaard and Philippe Lacherez.
