Effect of Movement on perception in non human primates & Dinosaurs

The ability to recognize the faces of conspecifics is a significant socio-cognitive ability in both humans and primates, for it helps to establish long-lasting relationships with multiple members of a group. Humans have a remarkable ability to remember and differentiate between several faces over their lifetime. Facial recognition is a complicated task that requires a holistic processing strategy. 

It has been found that the fusiform face area, the occipital face area, the superior temporal sulcus, the anterior/inferior cortex of the temporal lobe, and the amygdala all played roles in facial recognition in a study by Rossion, Hanseeuw, and Dricot. Another critical factor in perception is the steady gaze, which comes from the vestibular system. In humans, optic flow is determined to tell which world the direction is moving in, apart from the vestibular system. As we are moving forward, the things in the world are moving backward. It only tells us which direction we are headed and our head movement. The object flow information comes from the midbrain and has no connection to the visual cortex.

Interestingly, the neurons that carry information from the vestibular system are the same that carry information from optical flow. Thus when we are sitting on a train, and we look out, we cannot tell if we are the ones moving or the other train, only when one of the trains is moving at a slow speed. Humans cannot perceive movements below a minimum speed of about that of a minute hand on a watch. The movement can only be inferred. Moreover, motion is perceived as a blurred streak at high speeds rather than a definite object in motion.

Whereas very little is known about the ability of non-human primates to recognize faces through cognitive and neural processes such as in humans. We have some idea of how non-human primates and dinosaurs roamed about the world during their time, thanks to their depiction in movies in Planet of the Apes and Jurassic Park. Where chimpanzee perception can be studied to an extent, dinosaur perception and movement can only be speculated. 

The study of primates by various researchers has found a strong attraction toward first-order face configuration (The basic arrangement of eyes is above the nose, which is above the mouth). The first order of recognition helps differentiate between the face and non-face objects. The second type, called second-order face recognition (Diamond & Carey), provides the information needed to discriminate between individuals, for each face has unique cues such as shading and pigmentation. Sugita (2008) showed that after six months of face deprivation, the viewing preference and discrimination performance of the monkeys became biased towards the faces of the species to which they were first exposed. It has been seen that infant chimpanzees preferred their mother’s face at about two months’ age and showed no preference between mothers’ faces and unrelated individuals when they were one-month-old (YIN 1969). 

Face Inversion Technique 

Famous face recognition testing in both human and non-human primates has shown varied results when tested in monkeys and had stable results in the case of humans. In one study (Parr L. A., Dove T., Hopkins W. D. 1998), chimpanzees used a joystick-controlled cursor to select one of two inverted faces that matched an upright sample face on a computer monitor. Significant inversion effects were found for unfamiliar chimpanzees and human faces, the two species for which subjects had the expertise, but not capuchin monkey faces or automobiles, faces, and objects for which subjects were naive. Another study ( Tomonaga M., Itakura S., Matsuzawa T. 1993) tested the ability of one female chimpanzee to name human faces, individuals with whom she was familiar, using symbols. Perhaps because of the personal familiarity of these individuals with the subject or how she learned to associate their faces with specific lexigrams, this individual did not appear to use a holistic-processing strategy when presented with inverted faces.

The effects of stimulus movement on temporal perception

In a study by SCOTT W.BROWN (1995), it has been shown that stimulus motion lengthened perceived time. His experiments showed the following results :

  1. Stimulus motion lengthened perceived time.
  2. Faster speeds generally lengthened perceived time to a higher degree than slower speeds.
  3. The time judgments for both stationary and moving stimuli confirmed Vierordt’s law.
  4. The number of stimulus elements had only a limited influence on time judgments. 

The relation between movement and perception between lower and higher animals

It has been seen that the eyes of lower animals respond selectively to information that is vital to survival. For example, electrical patterns from a frog’s eye show that some elements in the organ respond only when the stimulus is about the size of a fly moving in the insect’s range of speed. The retina is responsible for most of the visual processing. Whereas in higher animals, perception works in elaborate ways. The brain is being involved at a higher rate than in lower animals. The retina in higher animals has a zone-specific for color and pattern vision, which is sensitive to the outer visual field. At the same time, the peripheral retina is sensitive to movement, which is usually a signal of danger in the wild. This can explain why the dinosaur in the Jurassic Park movie did not see the human hiding right in front of him, for his visual cue might have come from movement, and the human was standing still. 

“Don’t move, he can’t see us if we don’t move.”

The depiction of dinosaurs in Jurassic Park movies and Crystal Palace Park theme park came under fire for misrepresenting science. The viewers loved the monsters, but academics criticized them. Although with, ongoing discoveries of dinosaurs fossils around the world are proof that real and reel dinosaurs were different. Furthermore,  

In the same year, when everyone heard Dr. Alan Grant say this sentence on-screen on the first Jurassic Park movie, a researcher at the University of Oregon, Professor Kent Stevens, was developing digital models of the infamous Tyrannosaurus rex and Velociraptors to map the binocular fields of view and depth perceptions of the dinosaurs. Publishing his results in 2006, he claimed that the broader an animal’s binocular range is, “the better its depth perception and capacity to distinguish objects – even those that are motionless or camouflaged.” The idea that Trex has a good vision comes from the fact that he has forwards facing eyes.

The placement of eyes varied in plant-eating and meat-eating dinosaurs. Meat-eating dinosaurs generally had forward-facing eyes, which gave them a wide range of binocular vision and a narrow range of monocular vision, as opposed to most plant-eating dinosaurs that had eyes on the side of their heads, resulting in a wide range of monocular vision and a very narrow range of binocular vision. 

Further investigation revealed that the T. rex might have had visual clarity up to 13 times greater than a human! That is pretty impressive, and if it is true, Dr. Grant would not have stood a chance while standing mere three feet away from the Dinosaur nostrils in the movie. 


Sugita Y. 2008. Face perception in monkeys reared with no exposure to faces. Proc. Natl Acad. Sci. USA 105, 394–39810.1073/pnas

Yin R. K., 1969. Looking at upside-down faces. J. Exp. Psychol. 81, 141–14510.1037/h0027474

Parr L. A., Dove T., Hopkins W. D. 1998. Why faces may be special: evidence for the inversion effect in chimpanzees (Pan troglodytes). J. Cogn. Neurosci. 10, 615–62210.1162/089892998563013

Tomonaga M., Itakura S., Matsuzawa T. 1993. Superiority of conspecific faces and reduced inversion effect in face perception by a chimpanzee. Folia Primatol. 61, 110–11410.1159/000156737 

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