Emergency Alarm

Synonyms / Other Terms Used

Emergency Alarm Point, Alarm Point, Emergency Button, Emergency Signal

Category

Regulations, Safety, Safety Signs, Safety Action

Message / Function

To indicate the location of or direction to a control that when activated triggers an alarm for calling help in case of an emergency

	Source	Description
	ÖNORM A 3011	Hand (plan view) with one finger extended, above dot in square (outlined) broken at bottom plus letters SOS
	Tern	Hand (plan view) with one finger extended, above dot in square (outlined) broken at bottom plus letters SOS
	CNIS	Hand (plan view) with one finger extended, above dot in square (outlined) broken at bottom plus letters SOS
	Eco-Mo Foundation	Letters SOS, hand (plan view) with one finger extended touching circle
2)	ON Testdesign	Hand in plan view with one finger extended and pointing downwards towards dot with letters SOS on the right
3)	ON Testdesign	Hand in plan view with one finger extended and pointing downwards towards dot, text ALARM below
	Transport for London	Left hand with one finger extended in plan view, above dot in outlined square (broken at bottom)
	CRRC	Right hand with one finger extended in plan view, above dot in outlined square (broken at bottom)
	Tern	Letters SOS
4)	ON Testdesign	Capital letters SOS
5)	ON Testdesign	Capital letters SOS arranged diagonally from bottom left to top right
6)	Unknown	White square with bold circle inside, text ALARM on background below
	Boris Farias	Side view of beacon with three lines indicating light
	IEC 60417	Equilateral triangle, two concentric arcs on the right
	Hora III:EL	Equilateral triangle, two concentric arcs on the right

Note: Some of the examples shown above were mirrored horizontally to contrast differences.

Discussion

The number of image contents used in pictograms or graphical symbols to indicate the location of or direction to a control that when activated triggers an alarm for calling help in case of an emergency is rather limited. Several organizations rely on pictograms showing a hand with one finger extended to press a button, and added the letters SOS to make the message clear. Other variants, as the examples based on a side view of a beacon or the hazard warning triangle, are less common.

Studies regarding different cultural backgrounds conducted in several countries present research covering a cross section of the pictogram variants in use for this referent:

In Appropriateness Ranking Tests conducted in Austria (Brugger, 1984) and Sweden (Gärling, 1985) a total of seven variants were studied for the referent Emergency Call. The function was defined as To indicate the location of or direction to a control that when activated emits an emergency signal in a monitoring center. This also may be voice communication. In both countries the pictogram displaying a telephone handset with the letters SOS was generally preferred to all other variants, and a telephone handset in outline with an exclamation mark on the right was judged as least comprehensible. The numbering 2) to 6) reflects the final rank order after merging results from both studies and disregarding the telephone based versions.

In the following ISO comprehension test series, conducted in Australia, Austria, Hungary, Japan, and the United Kingdom (Brugger 1987), besides a telephone based version the two pictograms marked with 2) and 5) above were examined. The variants displaying additional elements in combination with the letters SOS were understood better than the three letters SOS alone as presented in the testdesign marked with 5), which performed less well especially in Japan. Pictogram 2) reached 75.8 % correct, compared to 58.8 % for the variant with SOS only. Regarding wrong responses like Entrance or Access Road, the author recommended a redesign of the button displayed corresponding to the rendering used in Fire Alarm.

Data regarding safety signs available from the Eco-Mo Foundation (2001) is based on a multiple choice format with only four possible choices. Under such conditions - even if the symbol used is far from perfect - results with correct responses close to 100 % are to be expected in case distractors used are not flawless or reasonable enough. The pictogram labeled Eco-Mo Foundation reached a score 87.8 in that study.

Recent research by Hung & Tan (2024) with a Chinese sample included the pictogram labeled with CRRC as part of the material used to study factors of sign comprehension. Even tested in white on red background, with a comprehension score of 52.3 % this variant exhibited an insufficient comprehension level among the sixty-five students who participated in this study.

Summarizing the findings of all studies, results indicate that variants just displaying the capital letters SOS or a hand with one finger extended to press a button are inferior to pictograms showing a combination of these elements. No data is available on the usefulness and comprehensibility of variants derived from the hazard warning triangle shown at the bottom of the table above.

Recommendations

Alarm

Based on test results available and also regarding research for Fire Alarm, we recommend the use of a pictogram like public information symbol No 113 from ÖNORM A 3011 part 6. To provide maximum visibility and readability, especially for persons with impaired vision, the letters S in SOS should be optimized like the letter S in the Tern regular typeface, to avoid confusions with the numbers five and eight.

Tests of pictograms of referent Alarm

Brugger, Ch. (1984): Reihungstest 1984. Report to the Austrian Standards Institute (ON) dated 19/84, Vienna.

Brugger, Ch. (1987): Evaluation of Public Information Symbols, ISO 1986 Test Series: Comprehension/Recognition Test. Vienna: ISO / TC 145 / SC 1.

Eco-Mo Foundation (2001): Test data of public information symbols in Japan - Procedure for the testing of public information symbols by the Study Committee. ISO: ISO/TC 145/SC 1 N 329.

Gärling, T. (1985): ISO Appropriateness Ranking Test 1985 - Redovisning av genomförande. Report to the Swedish Standards Institute dated 1985-07-24.

Hung Y-H & Tan Y. (2024): How symbol and text combine to promote sign comprehension: Evidence from eye-tracking. Displays. 83, 102709. https://doi.org/10.1016/j.displa.2024.102709