As we are contantly bombarded with vast amounts of information, selective attention mechanisms help us quickly attend to what is important while ignoring what is irrelevant. It makes ecological and evolutionary sense if important events can influence our spatial attention even before we become aware of the event. Recent studies have shown that subliminal presentation of emotional stimuli can modulate activity of the amygdala. Jiang et al ask whether activation of the emotional system directs observers' attention to the stimulus in the absence of awareness.
They show that information that has not entered our consciousness, such as interocularly suppressed (invisible) erotic pictures, can direct the distribution of spatial attention. They further show that invisible erotic information can either attract or repel observers' spatial attention depending on their gender and sexual orientation. While unaware of the suppressed pictures, heterosexual males' attention was attracted to invisible female nudes, heterosexual females' attention was attracted to invisible male nudes, gay males behaved similarly to heterosexual females, and gay/bisexual females performed in-between heterosexual males and females.
Here is their description of how information is presented so that it does not enter consciousness. "In the interocular suppression paradigm, a pair of high-contrast dynamic noise patches are presented to both sides of a fixation point in one eye, and a test picture and its scrambled control are presented to the fellow eye in spatial locations corresponding to the noise patches. Because of strong interocular suppression, the intact meaningful image and its scrambled control remain invisible for the period they are presented. If the suppressed images exert a location-specific effect on the attentional system, these images could potentially act as attentional cues that would influence the distribution of spatial attention and thus performance on a subsequent detection task."
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Figure: Schematic representation of the experimental paradigm for the invisible condition. For the visible condition, the noise patches were replaced with the same pair of intact and scrambled pictures presented to the other eye. In each trial, observers pressed one of two buttons to indicate the perceived orientation (CW or CCW) of a Gabor patch (the circle with lines in the right frame) briefly presented on either side of fixation. In the invisible condition, as shown, if observers detected any difference between the two sides of the fixation, they pressed another button to abort that trial.
Heterosexual male observers were more accurate at the orientation discrimination task when the Gabor targets followed the site of the invisible nude female pictures (attentional benefit) and were less accurate when the Gabor patches were at the site of invisible nude male pictures (attentional cost). Thus, heterosexual male observers' attention was attracted to nude female images and was repelled from nude male images, even though the images were not consciously perceived by the observers. Similarly, heterosexual female participants showed an attentional benefit (attraction) to invisible nude male pictures (positive attentional effect, although they did not show a significant attentional effect to invisible nude female pictures. Gay males had a similar pattern to female participants in that invisible female nude pictures did not attract their attention while male erotic images enhanced performance. Gay/bisexual females fell in-between the heterosexual male group and the heterosexual female group.