This is a summary of one of my works I did in a course of Duke University about Ponzo effect, this is a geometric-optical illusion documented by Italian psychologist Mario Ponzo in 1911. Is most commonly demonstrated by placing two identical horizontal lines between two oblique lines which are converging towards a central line in the horizon. Although the lines are physically identical, to the many people, the bottom line will appear to be smaller. And is a possible explanation of lunar illusion, with objects that seem "far away" (because they are "on" the horizon) that appear larger than objects "overload". Because, our brain does not estimate the real physical parameters of the objects, but approximates them by models that help to survive.
In this case a model representing depth view is most likely to be selected and two red lines do not have the same length according to it. It has been studied in many ways for more than a century and many plausible theories have been proposed, although a number of these are contradictory in their findings. It is inherently difficult to explain visual illusions, since an individual’s perception is by definition subjective and at odds with physical reality. But one of the best-known explanations depends on linear perspective, looking at two dimensions picture and transforming it mentally into a three dimensions image which portrays depth. For most people, the upper horizontal line looks larger, due to our interpretation of the converging lines as being parallel lines going off into the far distance. This is something we learn from repeated experiences. When more visual cues are added, the appearance of depth and therefore the strength of the Ponzo effect are enhanced.
Another explanation about the Ponzo effect is the Moon effect:
"Because in the horizon moon is perceived to be at the end of a stretch of terrain receding into the distance, accompanied by distant trees, buildings and so forth, all of which indicate that it must be a long way away, while these cues are absent from the zenith moon". (Kaufman and Rock, 1962).
This showed that a crucial causative factor in the illusion must be a change in the pattern of cues to distance, comparable to the Ponzo illusion. When pictorial cues to a great distance are subtracted from the vista of the large-looking horizon moon it looks smaller. Meanwhile pictorial cues to an increased distance are added into the vista of the zenith moon, it appears larger.
In this example, is more than meets the eye, because some cases visual perception does not perfectly correspond to the physical properties of objects. illustrations of the effect involve simple line drawings, but scenes from nature can also demonstrate the effect:
"It is not limited to Homo sapiens, but has been demonstrated in other species as well, including pigeons, rhesus monkeys and chimpanzees". (Fujita, 1997).
More researches has been conducted on the presence of the Ponzo effect along the human lifespan. Carl and Melissa Granrud has demonstrated:
"The effect can be observed in children as young as 4 years, and that it continues unchanged, even as people reach their 90 years". (Granrud, 2004)
Now my questions are ¿The humans perceive the ponzo effect from birth or develop through in a personal experience? ¿The ponzo effect influence in the develop of the vision? or ¿Can the effect ponzo show me a perception (Organic) problem? They are some questions but I found some interesting investigations about this point and the influence the cognitive and brain mechanisms in sensory substitution in people because, originally it was believed that young children could not see the illusion, that it gradually increased in magnitude, and then faded as people reached old age. So Sensory substitution appears as an interesting alternative for restoring some functions of a defective sensory organ (e.g., the sight in case of blindness). At the same time:
"Our knowledge about cognitive and brain mechanisms involved in sensory substitution has grown considerably, bringing new insights into human perception". (Renier and Volder, 2005).
So the explanation is necessary to determine whether susceptibility to the illusion is present immediately after birth however, eliciting reliable responses from newborns is fraught with operational difficulties, and studies with older infants are incapable of resolving this issue:
"For example childrens who were congenitally blind in both eyes from cataracts were operated on and gained sight at the relatively late age of 8 to 16 years. Although they did not develop perfect vision, they were able to perceive the Ponzo effect (and also the Mueller-Lyer) within 48 hours of their surgery". (Gandhi, Kalia, Ganesh, Sinha 2015).
The possible experiment If we want to know the influence Ponzo effect in develop of vision and detectec some problems in the vision. We could present this test like a game and give the basic test pattern to children 2, 3, 4, and 5 year olds in some kind of organized child-care setting; each child would be tested individually. They would be asked to point out the longest line they see in a touch-screen diagram of the Ponzo effect. If the studies of newly sighted children are correct, then we would expect to see the Ponzo effect in children from very early on. And if the children cant see it, we can recognize tsome anomaly or problem in his perception and take measures to prevent future diseases or malformations.
My consensus of this work and the knowledge acquired in this course was not everything we see is a reflection of reality! We need more studies and experiments about perception and the influence in how see the reality and the mechanisms to explain about what we see. Our development of the vision it´s a product of trial and error have influenced our in our adaptation experience and it is a key to understand the subjetivity between our visual experiencie and the recognition of the reality. Because, our ability evolved to correctly estimate the situation is crucial for the survival. Also the study and conection of visual perception with the neurosciences to keep studying the brain and his influence in human behaivor. It would also be beneficial to continue testing of children with pathologies, like blindness, congenital cataract and others anomalies could be identified and treated in the develop with best results.
Bibliography:
Fujita, K. (1997) Perception of the ponzo illusion by rhesus monkeys, chimpanzees, and humans: similarity and difference in the three primate species.
Gandhi, T., Kalia, A., Ganesh, S., Sinha, P. (2015) Immediate susceptibility to visual illusions after sight onset.
Granrud, C. E., Granrud, M.A. (2004) Perception of the Ponzo Illusion: A lifespan study Journal of Vision, 4 (8): 757,757a.
Kaufman and Rock (1962) Moon effect.
Renier and Volder (2005) Cognitive and the brain mechanism in sensory substation of vision: A contribution to the study of human perception.
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