Progression of Color Perception in Human Infants

| March 5, 2019

 

1.1            Background

Both electrophysiological and behavioural tests indicate that human colour vision seems to be very immature at birth) but they develop very fast over the first few months of living (Adams, 1998). For example, infants can exhibit a variety of chromatic discriminations by 3 months’ age, and sometimes those that colour-disabled grownups protanopes, and tritanopes are not in a position of making. This is an indication that human infants have both the functional short-term, mid-term and the long-term wavelength-sensitive cone systems residing on the child retina and they requisite neutral opponent channels within the CNS (central nervous system) which is under growth.

1.2            Research Theory

As Santrock mentions in the text, the visual system continues to develop after birth. It appears that experience is necessary for visual development to progress, and recent research suggests that experience may be equally important for colour perception. In one study, infant monkeys were raised in a room with only monochromatic illumination for almost a year (Mercer, 2014). These monkeys were able to match colours after extensive training, but their judgments were significantly different from those of infant monkeys who were not raised in the same environment. This suggests that early experience is important in the development of colour perception.

Research with human infants suggests that although human newborns (ranging from 1 to 7 days of age) are able to discriminate between certain colours, their ability to discriminate is vastly different from that of adults (Adams & Courage, 1998). The excitation purity levels that were necessary for infants to detect a difference between the colours green, red, and yellow from white were significantly higher than those necessary for adult perception. This research suggests that neonatal colour vision is quite poor.

1.3            Methodology

Research Design

Irrespective of the development of the techniques that are capable of measuring human infant colour vision, there is still no proper procedure comparable to the ones used on diagnosing the acquired colour vision and well-identified anomalies in the older children, grown-up adults and the clinical patients.

For this research, a pseudoisochromatic experiment was modified to create a more suitable and reliable test for young infants. The study used a forced choice preferential looking procedure to test 216 with pseudoisochromatic targets that fell on either a blue/yellow or red/green dichromatic confusion. The babies were aged between 3 and 24 months. 22 colour-deficient and 220 colour-normal adults were also tested for comparison purposes.

Participants

The research participant was 216 healthy human babies aged 3 months to 23months. The male infants were 110 while the female infants were 106, with a median age of 13.6 months. Almost all the babies in the study were Caucasian. At birth, the least infant weighed 2500g, and the least gestation period was 38weeks, and the babies have since not reported any kind of neurological condition or abnormalities. Additionally, 220 colour normal adults were used as a comparison for the test the adults were aged between 18 to 45 years, and there were 108 females and 112 male participants. Another 22 adults who had colour deficiencies also took part in the study, they had a median age of 29years, 3 females and 19males. All the participants in this study agreed to participate voluntarily. The participants were contacted directly from the hospital contacts through different methods including phone calls, emails and posters.

1.1            Results and Discussion

Infants

The results revealed that all the babies who participated easily detected the achromatic target, and this is an exception of a single female infant 6 months old. All the infants detected the B/Y plate target. The pattern was however very different from the R/G plate. Out of 208 infants, only 112 of them indicated evidence of detecting R/G plate (54% of the infants). However, as can be observed from the solid bar in figure 1 below, this rate had significant variations across age, with 86% of the older babies (17 to 23 months old babies) indicated evidence of detecting R/G target plate, a rate of failure of 14% that starts to approach the expected 8% value for all types of R/G color deficiency within the sample population (Bornstein et al., 1976).

On the other hand, the younger babies showed much higher relatives rates of failure. General estimation of the binominal studies (having p = 0.08, q = 0.92) gave the confirmation that both 3months to 9 months’ babies (z = 18.69, p < 0.001) and 10months to 16months infants (z = 12.36, p < 0.001), but not the older infants aged 17months and above olds (z = 1.48, n.s.) which indicated significantly higher levels of failure rates compared to the genetic expectation.

Adults

It was expected that the adult participants with a normal vision would see all the plate targets. It was expected that those with no colour vision would only see the achromatic demonstration plate, and those with R/G deficiencies would only see achromatic and the B/Y plate targets and the participants with B/Y deficiencies would only see R/G plates and achromatic.

The research results confirmed that all the adults detected both the B/Y plate and the achromatic demonstration plate on 100% trials. The results, therefore, confirmed that no adult showed a B/Y colour anomaly. Only one male participant returned a 90% outcome (short of 10% only), with the visually not-impaired adults reporting a detection of R/G plate target with a 100% level of accuracy.

 

The study results indicated that all the adults and infants who participated in the experiment passed the B/Y target but most of the younger infants failed the R/G target. This failure by the younger babies can be can be justified by the fact that the interaction of the loose maturities that resides in the tiny CIE vector distance and the visual system within the R/G target plate.

However, the older infants aged 17 to 23 months, colour defective adults and the colour normal adults all performed as expected. It was however interesting to note that the R/G plate performance was better amongst the female babies, well going above the rate of genetic dimorphism between the genders. In general, with additional changes and customization, the experiment serves as a potential tool for the detection of human infants colour vision problems in the infants or in early stages of life.

Conclusion

The findings from this study increased the minimal age limit for the diagnostic-based colour vision experiment in early human life. Extra modifications for the Pease and Allen test to integrate even more simple stimuli, like the ones with broader spectral separation, or to promote a more persistent with the individual babies, will most probably extend the age range into even early infancy. Such improvements in the development of experiments will be of specific benefit to both clinicians and scientists interested in either identification of earlier life colour vision anomalies, early integrity markers of the geniculostriate pathway and or the early environmental insult effects on the development of the critical human neural systems.

This study was congruent to earlier research studies which confirmed that both electrophysiological and behavioural tests indicate that human colour vision seems to be very immature at birth) but they develop very fast over the first few months of living (Bornstein et al., 1976). The study further confirmed that human infants have both the functional short-term, mid-term and the long-term wavelength-sensitive cone systems residing on the child retina and they requisite neutral opponent channels within the CNS (central nervous system) which is under growth. This finding justifies the faster growth in infants’ vision.

References

Adams, R. J., & Courage, M. L. (1998). Human newborn colour vision: Measurement with

chromatic stimuli varying in excitation purity. Journal of Experimental Child Psychology, 68, 22–34. Retrieved online on 10th Feb 2018 from, https://pdfs.semanticscholar.org/3fb4/75589df0eda443bbb5d5d73166cf173dbb42.pdf

Bornstein, H., Marc & Kessen, William & Weiskopf, Sally. (1976). Color Vision and Hue

Categorization in Young Human Infants. Journal of experimental psychology. Human perception and performance. 2. 115-29. Retrieved online on 10th Feb 2018 from, https://psycnet.apa.org/doi/10.1037/0096-1523.2.1.115

Mercer M., Drodge S., Courage M., and Adams R. (2014). A Pseudoisochromatic Test of

Color Vision for Human Infants. Retrieved online on 10th Feb 2018 from, https://doi.org/10.1016/j.visres.2014.04.006

Pease P.L. and Allen, J. (1988).  A new test for screening colour vision: Concurrent validity

and utility American Journal of Optometry and Physiological Optics, 65 (9), p. 729. Retrieved online on 10th Feb 2018 from, https://europepmc.org/abstract/med/3263804

Get a 5 % discount on an order above $ 150
Use the following coupon code :
2018DISC
Accounting homework help
Writing Assignment: News Story

Category: Completed Assignments

Our Services:
Order a customized paper today!