Baby vision at 3 months

The 95 % range at this age runs from 1.04 to 4.41 cycles per degree. Individual babies vary enormously, and a figure quoted without that band is a figure quoted misleadingly.

Colour

On the red–green axis the model puts chromatic discrimination at about 100 % of its mature value at this age, and on the blue–yellow axis about 100 %. Both channels are working within the first couple of months — the common claim that babies cannot see blue for months has weaker support than it sounds.

Why other sources give a bigger number

Measured by recording the brain’s response to a grating rather than by watching what a baby looks at, the same age gives about 7.3 cycles per degree instead of 2.14 — a factor of 3.4. Neither is wrong: the brain’s response estimates the detail the eye and early brain pass along, while watching what a baby looks at estimates what the baby demonstrably responds to. This site reports what babies look at, because that is the question a parent is asking.

Hearing

At this age a sound has to be about 22 dB louder than it does for you before a baby responds to it at all. The gap closes from the top down: high frequencies are close to adult within the first year, and low frequencies take until school age.

The longer answer

Accommodation stops being the variable thing it was: up to about three or four months the steady focus error shrinks and focus follows changes in distance more closely. It matters less than it sounds, because fine detail is not resolved at this age anyway and the range that counts as in focus is correspondingly wide.

Milestones

These are ranges from published studies, describing babies in general. They are not a checklist and this app never assesses your baby.

• Focusing settles down — Focusing is variable at first and steadies over the first three to four months. It matters less than it sounds: fine detail is not resolved at these ages anyway, so the range that counts as in focus is very wide and focusing error is not what limits what a baby sees.
• Depth from two eyes — Depth perception from the small difference between the two eyes’ views appears quite suddenly, usually somewhere between three and five months, rather than creeping in. It cannot be shown on a flat screen, so this app describes it and does not try to draw it.
• Detail, several times over — Over the first three months the finest pattern a baby can resolve roughly quadruples, and over the first year it grows about fourteen-fold. It is still around a quarter of an adult’s at the first birthday, and it goes on improving for years afterwards.
• The world gets wider — The area a baby responds to things in is narrow at birth and widens through the first half-year. This app describes it rather than drawing a dark ring around the picture, because a ring would claim a sharp edge that the measurements do not have.
• Faster flicker becomes visible — In the first weeks a light has to flicker more slowly before a baby can see it flickering at all — flicker an adult still notices already looks like steady light to them. This reaches near-adult values within the first few months. It is described here rather than shown, because slowing a camera preview would stand in for something these studies did not measure.

Sources

• Banks, M.S. & Salapatek, P. (1978). "Acuity and contrast sensitivity in 1-, 2-, and 3-month-old human infants." Investigative Ophthalmology & Visual Science 17(4), 361–365.
  Acuity estimated a different way, from where full contrast sensitivity functions cut off, and the very low spatial frequency of peak contrast sensitivity in early infancy.
• Banks, M.S. (1980). "The development of visual accommodation during early infancy." Child Development 51(3), 646–666.
  That steady-state focus error and accommodative response slope improve up to about 3–4 months, and that accommodative error does not meaningfully limit infant acuity.
• Braddick, O., Atkinson, J., French, J. & Howland, H.C. (1979). "A photorefractive study of infant accommodation." Vision Research 19(12), 1319–1330.
  Consistent focusing behaviour at a low accommodative demand of about 1.3 D (≈ 75 cm) emerging between 3 and 6 months.
• Clavadetscher, J.E., Brown, A.M., Ankrum, C. & Teller, D.Y. (1988). "Spectral sensitivity and chromatic discriminations in 3- and 7-week-old human infants." Journal of the Optical Society of America A 5(12), 2093–2105.
  That few 3-week-olds show reliable chromatic discrimination while most 7-week-olds do, and the long-wavelength advantage at 3 weeks.
• Haynes, H., White, B.L. & Held, R. (1965). "Visual accommodation in human infants." Science 148(3669), 528–530.
  The median 19 cm focus distance in alert newborns — the origin of the "babies see 8–12 inches" claim, cited so the app can state what the paper does and does not support.
• Held, R., Birch, E.E. & Gwiazda, J. (1980). "Stereoacuity of human infants." Proceedings of the National Academy of Sciences 77(9), 5572–5574.
  The abrupt onset of stereopsis between about 3 and 5 months — explained in the app and never drawn, because a flat screen cannot present it.
• Mohn, G. & van Hof-van Duin, J. (1986). "Development of the binocular and monocular visual fields of human infants during the first year of life." Clinical Vision Sciences 1(1), 51–64.
  The restricted newborn visual field and its expansion over the first year — described in the app, deliberately not rendered as a vignette.
• Neijzen, C.M., de Wit, F.M., et al. (2025). "Reference values for the Teller Acuity Cards II (TAC II) in infants and preverbal children, a meta-analysis." Acta Ophthalmologica. doi:10.1111/aos.17447.
  The behavioural binocular grating-acuity curve the app renders, and its stated uncertainty of approximately 0.16 log10 units, flat with age.
• Norcia, A.M. & Tyler, C.W. (1985). "Spatial frequency sweep VEP: visual acuity during the first year of life." Vision Research 25(10), 1399–1408.
  The swept-VEP acuity curve reported alongside the behavioural one as an upper bound, and the 24.3 c/deg adult reference measured in the same apparatus.
• Norcia, A.M., Tyler, C.W. & Hamer, R.D. (1990). "Development of contrast sensitivity in the human infant." Vision Research 30(10), 1475–1486.
  Contrast threshold at low spatial frequency falling from 7 % at 2–3 weeks to a 0.5 % asymptote by 9 weeks, against an adult 0.32–0.22 %, and the two-phase shape of contrast development.
• Peeples, D.R. & Teller, D.Y. (1975). "Color vision and brightness discrimination in two-month-old human infants." Science 189(4208), 1102–1103.
  Established red/white chromatic discrimination at two months of age.
• Regal, D.M. (1981). "Development of critical flicker frequency in human infants." Vision Research 21(4), 549–555.
  Low critical flicker fusion frequency in the first weeks reaching near-adult values within months — described, not rendered.
• Skelton, A.E., Maule, J. & Franklin, A. (2022). "Infant colour perception: Insight into perceptual development." Child Development Perspectives 16(2), 90–95.
  The review timeline placing the emergence of colour vision between about 3 weeks and 3 months.
• Varner, D., Cook, J.E., Schneck, M.E., McDonald, M. & Teller, D.Y. (1985). "Tritan discriminations by 1- and 2-month-old human infants." Vision Research 25(6), 821–831.
  Demonstrable tritan (S-cone) discrimination at 1 and 2 months, which is why the app does not dramatise a months-long absence of blue-yellow vision.
• ISO 226:2003, Acoustics — Normal equal-loudness-level contours; with Fastl, H. & Zwicker, E. (2007). Psychoacoustics: Facts and Models, 3rd ed. Springer (minimum audible field).
  The adult minimum-audible-field reference curve that the infant elevation is added to.
• Olsho, L.W., Koch, E.G., Carter, E.A., Halpin, C.F. & Spetner, N.B. (1988). "Pure-tone sensitivity of human infants." Journal of the Acoustical Society of America 84(4), 1316–1324.
  The primary pure-tone threshold dataset underlying the infant audiogram.
• Werner, L.A. (2002). "Infant auditory capabilities." Current Opinion in Otolaryngology & Head and Neck Surgery 10(5), 398–402.
  Behavioural thresholds of 40–55 dB SPL at 1 month falling to 10–30 dB SPL by 6–12 months; a 4 kHz threshold only ~10 dB above adult at 6 months while low frequencies mature into childhood; and that cochlear function is mature at term, so the elevation is middle-ear and central.

This is not a vision or hearing test. If anything worries you, speak to your paediatrician or a paediatric eye doctor.

This is a perceptual approximation, not a reconstruction of what your baby sees. Real babies vary a great deal from one another.

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