How do different keycap profiles (such as Cherry, SA, and XDA) impact typing comfort and key actuation on the Dactyl Manuform's unique ergonomic layout

Abstract

Research indicates that keycap profile characteristics like travel distance and height affect typing force and ergonomic comfort on ergonomic keyboards. However, specific comparisons between Cherry, SA, and XDA profiles on the Dactyl Manuform are lacking.

Keycap profile design factors—such as key travel distance, height variation, and overall shape—alter actuation forces and ergonomic comfort on keyboards with split or adjustable layouts similar to the Dactyl Manuform.

• Kia et al. (2019) report that ultra‐low travel keycaps (0.5-1.6 mm) lower required typing force compared to a conventional 2.0‐mm profile, though users preferred conventional designs.
• Miller et al. (2018) observe that shorter travel and lower actuation force correspond with reduced muscle activity and subjective fatigue.
• Platte (2022) notes that customizable keycap profiles can boost operational efficiency, showing a 20% decrease in task time over three months in one experiment.

Other studies document that profile features in various ergonomic keyboard designs (gull-wing, adjustable, split) improve wrist posture and reduce forearm pronation. Measured differences in typing speed are typically less than 5 WPM, and accuracy variations are under 3%.

Although no study directly compares Cherry, SA, and XDA profiles on the Dactyl Manuform, these findings suggest that subtle changes in keycap geometry can meaningfully influence the balance between actuation force and user comfort on similarly structured ergonomic layouts.

Methods

We analyzed 10 papers selected from an initial pool of 50, using 7 screening criteria. Each paper was reviewed for 6 key aspects relevant to the research question.

Results

Characteristics of Included Studies

The following table summarizes the key characteristics of the studies included in this review:

The report includes 10 studies examining various aspects of keyboard design and their effects on user performance and comfort. Key characteristics of these studies include:

• Study designs:
  • Laboratory studies (3)
  • Review (1)
  • User-centered evaluation (1)
  • Intervention study (1)
  • Real-life experiment (1)
  • Workplace evaluation (1)
  • Other experimental designs (2)
• Focus areas:
  • Keyboard design (6 studies)
  • Keyboard switches (2 studies)
  • Keyboard type (1 study)
  • Keycap profiles (1 study)
• Keyboard types:
  • Split keyboards (5 studies)
  • Conventional or standard keyboards (2 studies)
  • Other types (ultra-low travel, mechanical, varying switch forces) (1 study each)
• Measurement methods:
  • Typing performance (6 studies)
  • Wrist posture (4 studies)
  • Muscle activity (EMG) (3 studies)
  • User preference and comfort (2 studies each)
  • Other measures (forearm posture, typing force, fatigue, pain) (1-2 studies each)

We didn’t find specific measurement information in the abstract for 1 study.

Physical Design Impact

Keycap Profile Characteristics

This table details the physical characteristics of keycaps and keyboards examined in the studies:

Key findings from the keycap profile characteristics table:

• Profile types:
  • Split keyboards (4 studies)
  • Adjustable keyboards (2 studies)
  • Other types (ultra-low, ergonomic, gull-wing, mechanical, customizable, varied force, gabled, and angled) (1 study each)
• Height variation:
  • Specific measurements found in 1 study (0.5-2.0 mm range)
  • Varied heights mentioned without specifics in 2 studies
  • No mention found in abstracts for 7 studies
• Actuation impact:
  • Improved posture (wrist, forearm, or hand) (6 studies)
  • Other impacts:
    • Less typing force (but less preferred)
    • Shorter travel and lower force preferred
    • Improved typing efficiency
    • Higher force increased muscle activity
    • Improved comfort
    • Reduced productivity
• No mention found of surface contour in 9 out of 10 studies

Ergonomic Effects

Typing Biomechanics & User Comfort Metrics

Ergonomic outcomes, including comfort and muscle activity, are summarized below:

Key findings from the user comfort metrics table:

• Measurement types:
  • Self-reported measures (comfort, preference, or fatigue) (4 studies)
  • Musculoskeletal pain (1 study)
  • No mention found in abstracts for 5 studies
• Comfort ratings:
  • Alternative keyboards preferred (3 studies)
  • Conventional keyboards preferred (2 studies)
  • No difference reported (1 study)
  • No mention found in abstracts for 4 studies
• Muscle activity:
  • Reported in 3 studies with varying results
  • No mention found in abstracts for 7 studies
• Adaptation periods:
  • 10 hours or less (3 studies)
  • Longer than 10 hours (2 studies)
  • No mention found in abstracts for 5 studies

Performance Implications

Speed, Accuracy & User Adaptation Patterns

Impacts on typing performance and user adaptation are outlined here:

Key findings from the user adaptation patterns table:

• Typing speed impact:
  • No significant change (2 studies)
  • Lower or reduced typing speed (2 studies)
  • Improvement (1 study)
  • Difference of less than 5 WPM (1 study)
  • No mention found in abstracts for 4 studies
• Accuracy impact:
  • No significant change (1 study)
  • Difference of less than 3% (1 study)
  • No mention found in abstracts for 8 studies
• Adaptation patterns:
  • Within 10 minutes (1 study)
  • Between 1-24 hours (2 studies)
  • 7-14 days (1 study)
  • 3 months (1 study)
  • No mention found in abstracts for 5 studies

Reference