The Colavita visual dominance effect refers to the phenomenon in which study participants respond more often to the visual component of an audiovisual stimulus, when presented with bimodal stimuli.
Research has shown that vision is the most dominant sense for human beingsPosner, M.I., Nissen, M.J., Klein, M., (1976)"Visual Dominance:An Information Processing Account of its Origins and Significance" Psychological Review, 83(2):157-171 who do not suffer from sensory difficulties (e.g. blindness, cataracts). Theorists have proposed that the Colavita visual dominance effect demonstrates a bias toward visual sensory information, because the presence of auditory stimuli is commonly neglected during audiovisual events.
Francis B. Colavita, whom the Colavita visual dominance effect is named, was the first to demonstrate this phenomenon in 1974. Colavita's original experiments found that visual dominance for audiovisual events persists under a number of conditions, which has been further established as a robust effect by other researchers.
The Colavita visual dominance effect In 1974, Colavita conducted an experiment, which provided evidence for visual dominance in humans when performing an audiovisual discrimination task.Colavita, F.B. (1974). Human sensory dominance. Perception & Psychophysics,16(2), 409-412.
In his experiment, Colavita (1974) presented participants with an auditory (tone) or visual (light) stimulus, to which they were instructed to respond by pressing the ‘tone key’ or ‘light key’ respectively. Throughout the experiment, unimodal auditory trials, unimodal visual trials and a small number of audiovisual bimodal trials were randomly presented.
Colavita deceived the participants by informing them that the bimodal trials in the experiment occurred "accidentally". During practice trials, Colavita would "accidentally" present audiovisual stimuli, and would then draw the participants’ attention to what had just happened and would apologize for such ‘accident’. In addition, the participants were not instructed on how to respond on such trials or whether this type of trials would occur again.Koppen C., Spence C. (2007a). Seeing the light: exploring the Colavita visual dominance effect. Experimental Brain Research 180,737–754.
The results showed that participants had almost equivalent response times for auditory and visual stimuli in unimodal trials. Additionally, Colavita found that participants pressed the ‘light key’ in the majority of the bimodal trials. This was seen as evidence of visual dominance because participants failed to acknowledge the presence of the auditory stimulus in most bimodal trials. However, due to Colavita's deception of the "accidental" occurrence of bimodal trials, researchers have proposed that experimenter expectancy effects, task demands or methodological problems may have contributed to the visual dominance effect reported in Colavita's original study.Sinnett, S., Spence, C. & Soto-Faraco, S. (2007).Visual Dominance and attention: The Colavita effect revisited. Perception and Psychophysics, 69(5), 673-686. Nevertheless, subsequent experiments have discontinued the use of deception, and continue to show a robust Colavita visual dominance effect.
For example, Sinnet and his colleagues conducted an experiment in which they presented participants with three response keys, one for each type of response (unimodal visual, unimodal auditory and bimodal audiovisual); instead of just two, and they instructed participants to press the bimodal key when responding to audiovisual stimuli. This new manipulation resulted in a significant reduction of the Colavita effect because errors in bimodal trials were only committed in a small number of trials. In another experiment, Sinnett and his colleagues conducted a pre-specified target detection task where auditory targets were more frequent than visual or bimodal targets. This led to the elimination of the Colavita effect. The authors suggested that this was due to the introduction of a bias toward auditory stimuli.Koppen, C. & Spence, C. (2007b). Audiovisual asynchrony modulates the Colavita visual dominance effect. Brain Research, 1186, 224-232. Ngo and her colleagues conducted a similar study where the results were replicated, because their findings showed that under the appropriate conditions and task demand, the Colavita effect can be reversed.Ngo, M.K., Cadieux, M.L., Sinnett, S., Soto-Faraco, S. & Spence, C. (2011). Reversing the Colavita visual dominance effect. Experimental Brain Research, 214, 607-618. Also, Sinnett and his colleagues mention that animals and humans increase their reliance on auditory stimuli in high-arousal situations and when facing potential threats, which could imply that the Colavita effect is situation and context dependent.
Colavita also varied the intensity of the visual and the auditory stimuli to determine whether matching the intensity of both stimuli, or if increasing the intensity of only the auditory stimulus would decrease the occurrence of the Colavita effect. However, none of the experimental manipulations regarding the intensity of the stimuli decreased the occurrence of the Colavita effect. Further research has been conducted to replicate Colavita's experiment and to extend the Colavita effect to more complex stimuli. For example, Sinnett, Spence and Soto-Faraco conducted an experiment in 2007, in which pictures and sounds were used as stimuli instead of the light and tone. The rationale for using more complex stimuli was that this type of stimuli would increase perceptual load, requiring more attentional resources.Lavie, N. (2005). Distracted and Confused? Selective attention under load. Trends in Cognitive Sciences, 9(2), 75-82. The findings from this study showed that the Colavita effect continues to occur when stimuli become more complex.
Explanation of visual dominance effect According to Hartcher-O’Brien and colleagues, the Colavita and visual dominance effects can be generally attributed to an imbalance in the ability to access processing resources, namely between vision and other sensory modalities. Failure of a stimulus to access awareness when multiple stimuli are presented at the same time may result in sensory dominance.Hartcher-O'Brien, J., Levitan, C., Spence, C. (2010). Extending visual dominance over touch for input off the body.Brain Research, 1362: 48-55 For decades, there has been a continuous debate regarding whether the Colavita effect occurs at a sensory level or at the level of attention, involving exogenous (involuntary or reflexive) or endogenous (voluntary) attention. Research has found inconclusive results regarding this debate.
Posner and colleagues conducted a study to look at the origin and significance of visual dominance. They proposed that attentional resources are endogenously (voluntarily) biased towards vision in order to compensate for the low alerting capability of visual signals. Posner and colleagues proposed that visual stimuli do not alert attention automatically, whereas other sensory modalities do. In order for the visual stimulus to serve as an effective alerting mechanism, the person must process it through active attention. Consequently, when attention is directed towards vision, the attentive mechanisms to other sensory modalities are reduced. The low alerting capability of visual signals is compensated by individuals’ attentional bias towards visual modalities. This is viewed by Posner and colleagues (1976) as an endogenous (voluntary) strategy in responding to one's environment.
Conversely, Koppen and Spence suggest that attentional bias towards the visual modality may be exogenously (reflexively) mediated. That is to say, visual stimuli may in fact capture a person's attention more effectively than stimuli from other sensory modalities.
Koppen and Spence (2007a) investigated what role exogenous (reflexive) attention plays in sensory modality, and found that the Colavita effect can be regulated (but not terminated), depending on which sensory modality (audition or vision) individuals focus their exogenous attention on. Visual stimuli were more effective at capturing attention than auditory stimuli. Thus, Koppen and Spence propose that the Colavita effect may reflect differences in the exogenous attention-capturing qualities of visual versus auditory stimuli.
Sinnett, Spence, and Faraco (2007) conducted an experiment in which they noted that, when attention was manipulated in the direction of the auditory stimulus, the Colavita effect was able to be reduced, but not reversed, to create auditory dominance. As a result, they proposed that visual dominance cannot be based entirely on attentional mechanisms, but must occur at a sensory level. This inability to reverse the Colavita effect when attention is directed to an auditory stimulus, suggests that visual dominance may involve innate biases towards visual modalities. In one of their experiments, in order to reduce the magnitude of visual dominance, Sinnett and his colleagues (2007) created a strong bias towards the auditory modality. To do this, they increased the proportion of auditory targets, which resulted in faster reaction times to unimodal auditory targets than to unimodal visual targets. Participants showed a small (nonsignificant) bias towards making more erroneous unimodal auditory responses, and no reversal of the Colavita effect was observed. These results support the claim that visual dominance occurs at a sensory level, before the engagement of attention.
Another theory that has been used in the explanation of the Colavita effect is the ‘Failure of Binding’. This theory suggests that participants bind together the visual and auditory components of an audiovisual stimulus, which can hinder the processing of the auditory component of the audiovisual stimulus. This occurs because the visual component alone provides enough information about the audiovisual stimulus. This theory only applies when the visual and auditory stimuli presented are congruent. When they are incongruent, the visual component is not an accurate representation of the auditory component. In this case, incongruency can act as a cue to inform participants that a bimodal target occurred.
Spatial and temporal coincidence The Colavita effect has been shown to be affected by factors that contribute to the intermodal binding of auditory and visual stimuli during perception. These factors of interest are spatial and temporal coincidence between the auditory and visual stimuli, which modulate the Colavita effect through temporal separation and temporal order.