On desktop, a visual signal travels through the graphics/display pipeline and your response may come back through a mouse or keyboard. On mobile, the display and capacitive touchscreen are integrated into the same device but still have sensing, processing and operating-system delays.
A study measuring 26 smartphones reported wide variation in total visual-display plus touch-input latency across devices, roughly from tens of milliseconds to well over 100 ms.
For a full-screen simple reaction, both can be small movements. For aim tasks, touchscreen input lets you point directly at the location while a mouse moves a separate cursor through a control-display mapping.
That makes cross-device Aim comparisons especially difficult.
Modern phones may run at 60, 90, 120 Hz or dynamically change refresh rate. Desktop monitors may use 60, 144, 165, 240 Hz or other rates. Refresh interval is only one part of total latency, but it can change when a visual update becomes visible.
Power-saving modes can also alter a device’s refresh behaviour.
There is no universal answer. Some phones have excellent low-latency displays and touch systems; some computers have high-refresh monitors and low-latency mice; others are slower.
Without external calibration hardware, an online test cannot subtract every device-specific delay. Consistency is therefore more important than assuming one platform is inherently correct.
Direct touch, different hardware latency, refresh rate and movement mechanics can all contribute.
A low-latency mouse, high-refresh display or more consistent system timing can help, and the task may suit mouse input better.
For serious tracking, separate them. Reaction Lab’s device-comparison tools are designed around that idea.