Power cost should factor into whether haptics are used for low-priority cases
Aliases: cost benefit · low priority · design tradeoff
What it is
When deciding whether to add haptics to a low-priority case, power should be one of the criteria. A low-priority event yields limited haptic benefit while costing the same energy and attention as any other cue, so it should be the first thing excluded at equal return. This puts power into the design decision rather than treating it as later optimization.
Why it happens
Cost-benefit comparison must line up three costs: energy, attention, and discriminable capacity. Low-priority events tend to lose on all three—the energy equals that of any other cue, users read the attention cost as interference, and it consumes a limited pattern slot. Judging only by "would haptics help here?" inflates total haptic volume, which triggers habituation and wholesale disabling and drags down high-priority events with it. Making power explicit gives the tradeoff a defensible basis.
Studying it
Compare decisions under different criteria: one group decides purely on experience benefit, another adds energy and discriminable-capacity constraints, and compare resulting pattern counts, critical-event identification, and overall disable rate. Variables include constraint strictness and product type. Include user-side outcomes, not only design-side metrics.
Where it stops holding
For mains-powered products or contexts where power does not matter, the energy constraint can relax—but the attention and discriminable-capacity constraints should remain. If a low-priority event has no route on another channel, haptics may be the only option and power should not veto it. Constraint strictness must match device class, with wearables far tighter than desktop devices.
Applying it
- When considering haptics for a scenario, record estimated power, attention cost, and the pattern slot consumed.
- For low-priority cases that score high on all three costs, move to another channel or keep a record only.
- Periodically review shipped low-priority haptics and reclaim their resources.
- Verification: compare outcomes with and without cost constraints on critical-event identification and overall disable rate to confirm the constraints improved user-side results.
Related
- Within the group: D3.15.1 Sustained use of haptic motors measurably drains the battery · D3.15.2 High-rate haptic feedback needs restraint when battery is low
- Adjacent: D3.08.3 The haptic budget should follow event importance · D3.12.2 Graded control keeps critical haptics while silencing decorative ones
- Search terms:
design tradeoff·cost benefit·haptic budget