± Geometric Radar Symbology: Static Cathode Ray Tube Testing

Transcription

1 ± Gemetric Radar Symblgy: Static Cathde Ray Tube Testing 00 Gary G. Sa^i and Richard J. Carter US Army Research Institute fcr the Behaviral and Scial Sciences (ARI), Frt Bliss Field Unit, Ft Bliss, Texas V Many air defense (AD) systems use gemetric symbls t indicate aircraft n system displays and different shapes t encde friend-r-fe infrmatin. The purpse f ARI's AD symblgy research was t identify sets f gemetric symbls assciated with high discriminability and quick respnse times-r It was felt that AD persnnel wuld respnd fastest and mst accurately' t symbls with steretyped meanings. Phase 1 f this research (Carter, in press) identified nine such symbls: FRIEND: Circle (O). 5-Pinted Star (ft). Heart K?), Flag ( P") HOSTILE: Swastika (fe). Cllapsed Bx ()2t). The letter "X" (X) UNKNOWN: Questin Mark (?), 6-Sided "U" (U) ^- Phase 2, using paper displays, tested these symbls in sets f three ( 1 f each type) and five (2 friend, 2 hstile, and 1 unknwn) symbls. The three-symbl set with the quickest respnse time (RT) was Star-Bx-U; the ne with the least errrs was Heart-Bx-U. RTs fr the five-symbl sets were nt significantly different, but set Heart-Flag-Swastika-Bx-Questin Mark had the least errrs. (Carter, 1980] - ^This paper deals with Phase 3, in which the symbl sets were presented upn a cathde ray tube (CRT) display. Symbl shape was the independent variable; RT and errrs were the dependent variables. The hyptheses were that sme sets wuld have lwer RTs and errrs, and that the results f Phases 2 and 3 wuld agree. Experiments 1 and 2: Three-Symbl Sets Methd Subjects. Fr each experiment, 30 subjects were drawn frm a pl f enlisted persnnel (grades E2-E6) in AD cnsle peratr Military Occupatinal Specialties (16C, E, H, J) at the US Army Air Defense Center at Frt Bliss, TX. Apparatus. A PATRIOT Tactical Operatins Simulatr/Trainer (TOS/T) prvided a 36.2 cm diameter, rund CRT, as well as necessary switches and cntrls, including an ismetric jystick. A FORTRAN prgram was used t generate 64min-wide symbls n the CRT and t recrd the data. Prcedure. A 90 tp riented search sectr was pltted n the CRT (Figure 1). Each sldier, seated at the TOS/T cnsle, was given 2 practice The authrs wish t thank CPT David Smull, SP6 David Arvieux, Jeri Price, and Jhn Davis fr their valuable assistance. 605

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3 and 8 test sets (see Table 1) which each cnsisted f 1 friend, 1 hstile, and 1 unknwn. On each set, the sldier was shwn 27 scenes; each scene cntained 24 symbls (7 t 9 f each type). The 27 scenes were divided int 3 grups f 9 scenes; the sldier was tld t lcate and "hk" either the friend, hstile, r unknwn symbls in each grup. The sldier hked each symbl by using the jystick t superimpse a plus-sign-shaped cursr upn the symbl and then pressing the "hk" buttn. Feedback was prvided by causing a PATRIOT "hld fire" mdifier t appear arund the hked symbl. Results Experiment 1. The RTs fr the eight symbl sets were significantly different: FT7T203) = 2.391, P= A Newman-Keuls' test shwed that the sldiers hked the symbls in the Star-Bx-Questin Mark and Heart-Swastika- Questin Mark sets significantly faster than the tw slwest sets. The number f errrs made n the symbl sets were als significantly different,%2{7)=49 < 37 > p<.001, as were the numbers f errrs made n the tw hstile symbls,» 2(i)=7.i3 > p <.i. Symbl set Star-Bx-Questin Mark had the fewest errrs amng sets and the Cllapsed Bxes had fewer errrs than the Swastikas. Experiment 2. The RTs fr the symbl sets differed significantly: F{7,203)=2.283, p=.029; set Circle-Bx-Questin Mark was significantly faster than the slwest sets. The times fr the friend symbls were als different, F(3,87)=5.993, p=.0012, with the Circle being significantly faster than the Flag. The number f errrs were significantly different fr sets (x 2 (7)=14.87, p <.025), friends (x. 2 (3)sl7.16, p <.001), and unknwns {3fe Z (l)=7.13, p <.01). Set Circle-Bx-Questin Mark, friend symbl Heart, and unknwn symbl Questin Mark had the fewest errrs in their respective grups (see Table 1). Experiments 3 and 4: Five-Symbl Sets Methd Subjects. Fr each experiment, 24 subjects were selected in the same way as subjects in Experiments 1 and 2. Apparatus. The apparatus was the same as that used in Experiments 1 and 2. Prcedure. Each sldier was given 1 practice and 6 test sets (see Table 2) which each cnsisted f 2 friends, 2 hstiles, and 1 unknwn. On each set, the sldier was shwn 50 scenes; each scene cntained 25 symbls (4-6 f each shape). The 50 scenes were divided int 5 grups f 10 scenes each. The rest f the prcedure was the same as in Experiments 1 and 2. Results Experiment 3. The RTs were significantly different nly amng friend symbls: F (2,46)=6.707, p= A Newman-Keuls' test revealed that the Hearts were significantly faster than the ther friend symbls. The number f errrs were significantly different fr sets (*. 2 (5)=9.51, p <.05), and fr friend (X 2 (2) = 16.79, p<.01) and hstile (% 2 (2) = 12.52, p <.01) symbls. Set Star- Heart-Bx-X-Questin Mark had the lwest errr rate amng sets. Hearts and i

4 ('.' ': Table 1 Mean Respnse Times and Errr Rates fr Experiments 1 and 2 EXPERIMENT 1 EXPERIMENT 2 Sets RT ERRORS Sets RT ERRORS OXU (PRACTICE) -frxu (PRACTICE) rx? (PRACTICE) ^x? (PRACTICE) ^Fy? OFfP &W OM ^m? w? ^r^iu ^Ff? ^Fy? ra? ^FtU r&v ^« rsi? ^KU r^u Friends Friends ^r O ^ ^r Hstiles ^ > Ft M Hstiles Unknwns ' * w U Unknwns U MMJ

5 Swastikas had the lwest errr rates amng friends and hstiles, respectively. Experiment 4. Because nly ne unknwn symbl was used, nly sets, friend symbls, and hstile symbls were cmpared. The RTs fr the sets were nt significantly different, but the times fr the friend {F(2,44)=30.369, p -<.00005) and the hstile symbls (F(2,44)=7.510, p=.0019) were. Newman-Keuls' tests revealed that the Circle was significantly faster than the ther friends and that the X was significantly faster than the Cllapsed Bxes. The errrs were significantly different fr the sets {%2(5)=i9.44, p <:.01) and the friend symbls (% 2 (2)=55.64, p <.01). Set Circle-Star-Bx-X-Questin Mark and friend symbl Circle had the lwest errr rates fr their grups (see Table 2). Discussin The hyptheses that the symbls and symbl sets wuld have significantly different time and errr rates was generally supprted. Nte that respnse time differences were fund amng 3-symbl sets but nt amng 5-symbl sets. Inasmuch as the ttal number f symbls displayed at ne time were cmparable acrss the experiments, it is assumed that the effect f any ne symbl n respnse time decreases as the diversity f symbls displayed increases (Earl, in press). The hypthesis that the same sets and symbls wuld be identified as best in Phases 2 and 3 was nt supprted. This may be due t slight differences in the symbl shapes as displayed n the CRT versus n paper, the fact that CRT symbls were white-n-black instead f black-n-white, r differences in hking prcedures and practice sets. In general, the subjects in Phase 2 perfrmed better n the Flag and six-sided "U" but wrse n the "X" and Questin Mark than the subjects in Phase 3. Clearly, paper simulatins f CRT screens must be interpreted with great care. References Carter, Richard J. Paper-and-pencil testing f gemetric radar symbls. Prceedings f the Military Testing Assciatin, 1980, 22(1), CAR2-1 t CAR2-10. Carter, Richard J. An investigatin f gemetric radar shapes fr steretyping (ARI Technical Reprt). Alexandria, Virginia: US Army Research Institute fr the Behaviral and Scial Sciences, in press. Earl, William K. Learning and recgnitin f US, Sviet, and pictrial military symblgy. Alexandria, Virginia: US Army Research Institute fr the Behaviral and Scial Sciences, in press ' '-' ^. ^_. - -»^.^^^^

6 «. Table 2 Mean Respnse 1 "imes and Errr Rates fr Experi men"? 3 and 4 > m EXPERIMENT 3 EXPERIMENT 4 H Sets RT ERRORS Sets RT ERRORS Cx 1 rcxu (PRACTICE) rftfwu (PRACTICE) iiji 0 T ^ ^ U (PRACTICE) ^r^xu (PRACTICE) i ^^FfM? ^7 CMX(J (PRACTICE) 1 ^r^f^^u « OÄ»? 1 ^ftx? OiVFyx? I -J^ 151 X O^THXp ^rft!»? O^Ff '? ^rft!»?«*.«2.00 OWXP Friends ^^x9 H M Friends : >: : ^? O v P it Hstiles V Ft Hstiles M FH X M W Unknwns X r Unknwn U