Why your reaction time is slower on a phone

Where the delay comes from

Between the moment your finger touches the glass and the moment the page knows it, several things happen. The touch sensor scans at its own rate, the phone processes the signal, the browser turns it into an event. On the other side, the screen only shows the green when it refreshes, and the page cannot know exactly when your eyes saw it.

A mouse or a keyboard on a computer has its own delays too, usually shorter. That is why a reaction time is always the reaction of a person plus a device, never of a person alone.

What the studies show

A study of mobile cognitive tests reminds that conventional touchscreens add latencies of 50 to 200 ms, and that some systems use the phone’s motion sensor to bring that down to 1 or 2 ms (Van Patten et al., 2021). In that study, 55 adults took a reaction test on their own phones once a week for three weeks, and the test was reliable, 0.83, even with that delay (Van Patten et al., 2021). A device can be slow and still consistent.

A much larger study looked at 59,587 visitors to TestMyBrain.org, then 3,818 more. After accounting for age, gender, education and a vocabulary test, users of mobile devices, Android phones in particular, were significantly slower on reaction time tests than users of laptops and desktops (Passell et al., 2021). The authors attribute it to device latency.

The Headgame norm by type of screen

Public norms such as Human Benchmark mix every kind of device. Headgame is building a norm split by type of pointer, touch or mouse, from anonymous games on this site and in the app. It will be published here once each group reaches 1,000 games, with its exact sample size and date. Until then, this page gives no figure of its own rather than an estimate.

How Headgame corrects for it

The app records the model of phone and the refresh rate of the screen, nothing that identifies you, and adjusts reaction scores by type of screen when it computes your card. On this site, the percentile compares you with a public norm that mixes devices, and the page says so. The practical rule is simple. Compare yourself with yourself, on the same device.

Sources

1. Van Patten R., Iverson G.L., Muzeau M.A., VanRavenhorst-Bell H.A. (2021). Test-retest reliability and reliable change estimates for four mobile cognitive tests administered virtually in community-dwelling adults. Frontiers in Psychology 12, 734947. PMC8566921. doi.org/10.3389/fpsyg.2021.734947
2. Passell E., Strong R.W., Rutter L.A. et al. (2021). Cognitive test scores vary with choice of personal digital device. Behavior Research Methods 53(6), 2544 to 2557. PMC8568735. doi.org/10.3758/s13428-021-01597-3