Our limited understanding of dark matter and energy may be making us blind to signals from intelligent alien life, which possibly exist in dimensions that humans cannot perceive.
"When we think of other intelligent beings, we tend to see them from our perceptive and conscience sieve; however we are limited by our sui generis (unique) vision of the world, and it's hard for us to admit it," said Gabriel de la Torre, from the University of Cadiz in Spain.
"What we are trying to do with this differentiation is to contemplate other possibilities, for example, beings of dimensions that our mind cannot grasp; or intelligences based on dark matter or energy forms, which make up almost 95 per cent of the universe and which we are only beginning to glimpse," said de la Torre.
The researchers conducted an experiment with 137 people, who had to distinguish aerial photographs with artificial structures (buildings, roads) from others with natural elements (mountains, rivers).
In one of the images, a tiny character disguised as a gorilla was inserted to see if the participants noticed.
"It is very striking, but very significant and representative at the same time, how our brain works," said de la Torre.
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"Before doing the test to see the inattentional blindness we assessed the participants with a series of questions to determine their cognitive style (if they were more intuitive or rational), and it turned out that the intuitive individuals identified the gorilla of our photo more times than those more rational and methodical," he said.
"If we transfer this to the problem of searching for other non-terrestrial intelligences, the question arises about whether our current strategy may result in us not perceiving the gorilla," he said.
"Our traditional conception of space is limited by our brain, and we may have the signs above and be unable to see them. Maybe we're not looking in the right direction," de la Torre said.
"We can have the signal in front of us and not perceive it or be unable to identify it. If this happened, it would be an example of the cosmic gorilla effect. In fact, it could have happened in the past or it could be happening right now," he said.
In the study published in the journal Acta Astronautica, researchers also pose how different classes of intelligent civilizations could be.
They present a classification with three types based on five factors - biology, longevity, psychosocial aspects, technological progress and distribution in space.
An example of Type 1 civilisations is ours, which could be ephemeral if it mishandles technology or planetary resources, or if it does not survive a cataclysm.
However, it could also evolve into a Type 2 civilization, characterised by the long longevity of its members, who control quantum and gravitational energy, manage space-time and are able to explore galaxies.
The third type of intelligent civilization, the most advanced, would be constituted by exotic beings, with an eternal life, capable of creating in multidimensional and multiverse spaces, and with an absolute dominion of dark energy and matter.