The post-1965 literature on the use of secondary tasks in the assessment of operator workload was surveyed. Twelve classes of tasks were identified; the most frequently used were choice reaction time, memory, monitoring, and tracking. The literature review did not suggest a single best task or class of tasks for the measurement of workload. Limitations in using secondary tasks are discussed, and directions for future research are presented.
Get full access to this article
View all access options for this article.
References
1.
AdamthwaiteM.ShafferJ.Assimilation and attention in form perception. American Journal of Psychology, 1965, 73, 665–671. (1).
2.
AllenR. W.ClementW. F.JexH. R.Research on display scanning, sampling, and reconstruction using separate main and secondary tracking tasks. Hawthorne, California: Systems Technology, Inc., Report No. NASA CR-1569, July, 1970. (N70-33342) (2).
3.
AllportD. A.AntonisB.ReynoldsP.On the division of attention: A disproof of the single channel hypothesis. Quarterly Journal of Experimental Psychology, 1972, 24, 225–235. (3).
4.
AlluisiE. A.MorganB. B.Effects on sustained performance of time sharing a three-phase code transformation task (3P-COTRAN). Perceptual and Motor Skills, 1971, 33, 639–651. (4).
5.
AndersonP. A.ToivanenM. L.Effects of varying levels of autopilot assistance and workload on pilot performance in the helicopter formation flight mode. Minneapolis, Minnesota: Honeywell, Inc., Report No. JANAIR 690610, March, 1970. (AD-706 001) (5).
6.
BaddeleyA.The capacity for generating information by randomization. Quarterly Journal of Experimental Psychology, 1966, 18, 119–130. (6).
7.
BahrickH. P.NobleM.FittsP. M.Extra-task performance as a measure of learning a primary task. Journal of Experimental Psychology, 1954, 48, 298–302.
8.
BaronS.LevisonH.An optimal control methodology for analyzing the effects of display parameters on performance and workload in manual flight control. IEEE Transactions on Systems, Man, and Cybernetics, 1975, 5, 423–430. (7).
9.
BeckerC. A.Allocation of attention during visual word recognition. Journal of Experimental Psychology: Human Perception and Performance, 1976, 2, 556–566. (8).
10.
BensonA. J.HuddlestonJ. H. F.RolfeJ. M.A psychophysiological study of compensatory tracking on a digital display. Human Factors, 1965, 7, 457–472. (9).
11.
BergeronH. P.Pilot response in combined control tasks. Human Factors, 1968, 10, 277–282. (10).
12.
BeyerR.A limited study of the trade off between luminance and color coding in electronic aircraft displays. Proceedings of the Thirteenth Meeting of the Guidance and Control Panel of AGARD. Paris, AGARD-CP-96, October, 1971, (2)1-(2)9. (N72-22621) (11).
13.
BoggsD. H.SimonJ.Differential effect of noise on tasks of varying complexity. Journal of Applied Psychology, 1968, 52, 148–153. (12).
14.
BriggsG. E.PetersG. L.FisherR. P.On the locus of the divided-attention effects. Perception and Psychophysics, 1972, 11, 315–320. (13).
15.
BriggsG. E.WienerE. L.Influence of time sharing and control loading on transfer of training. Journal of Applied Psychology, 1966, 50, 201–203. (14).
16.
BroadbentD. E.GregoryM.On the interaction of S-R compatibility with other variables affecting reaction time. British Journal of Psychology, 1965, 56, 61–67. (15).
17.
BrownI. D.A comparison of two subsidiary tasks used to measure fatigue in car drivers. Ergonomics, 1965, 8, 467–473. (16).
18.
BrownI. D.Some alternative methods of predicting driver performance among professional drivers in training. Ergonomics, 1968, 11, 13–21. (17).
19.
BrownI. D.SimmondsD. C. V.TicknerA. H.Measurement of control skills, vigilance, and performance on a subsidiary task during 12 hours of car driving. Ergonomics, 1967, 70, 665–673. (18).
20.
BrownI. D.TicknerA. H.SimmondsD. C. V.Interference between concurrent tasks of driving and telephoning. Journal of Applied Psychology, 1969, 53, 419–424. (19).
21.
ChilesW. D.Objective methods for developing indices of pilot workload. Oklahoma City, Oklahoma: FAA Civil Aeromedical Institute, Report No. FAA-AM-77-15, July, 1977.
22.
ChilesW. D.AlluisiE. A.AdamsO. S.Work schedules and performance during confinement. Human Factors, 1968, 10, 143–196. (20).
23.
ChilesW. D.BruniC. G.LewisR. A.Methodology in the assessment of complex human performance: The effects of signal rate on monitoring a dynamic process. Washington, D.C.: Federal Aviation Administration, Office of Aviation Medicine, Report No. FAA-AM-69-6, April, 1969. (21).
24.
ChilesW. D.JenningsA. E.Effects of alcohol on complex performance. Human Factors, 1970, 12, 605–612. (22).
25.
ChilesW. D.JenningsA. E.WestG.AbernathyW. T.Multiple task performance as a predictor of the potential of air traffic controller trainees. Oklahoma City, Oklahoma: FAA Civil Aeromedical Institute, Report No. FAA-AM-72-5, January, 1972. (AD-741 736) (23).
26.
ChowS. L.MurdockB. B.The effect of a subsidiary task on iconic memory. memory and Cognition, 1975, 3, 678–688. (24).
27.
ChuY.RouseW. B.Optimal adaptive allocation of decision making responsibility between human and computer in multi-task situations. Proceedings of the International Conference on Cybernetics and Society. Washington, D.C., September, 1977, 168–175. (25).
28.
CliffR. C.The effects of attention sharing in a dynamic dual-task environment. Proceedings of the Seventh Annual Conference on Manual Control, University of Southern California, NASA SP-281, June, 1971, 307–325. (N73-10104). (26).
29.
ComstockE. M.Processing capacity in a letter-matching task. Journal of Experimental Psychology, 1973, 100, 63–72. (27).
30.
DamosD. L.The development and transfer of timesharing skills. Proceedings of the Human Factors Society Twenty-First Annual Meeting, San Francisco, California, October, 1977, 53–57. (28).
31.
DanevS. G.WartnaG. F.BinkB.RadderJ. J.LuteynI.Psychophysical assessment of information load. Nederlands Tijdschrift voor de Psychologie en haar Grensgebieden, 1971, 26, 23–29. (29).
32.
DanielJ.FlorekH.KosinarV.StrizenecM.Investigation of an operator's characteristics by means of factorial analysis. Studia Psychologica, 1969, 11, 10–22. (30).
33.
DempseyT. K.MorganB. B.Jr.Effects of time-sharing stress on skilled-performance of a digital-readout COTRAN task. Proceedings of the 77th Annual Convention of the American Psychological Association, 1969, 4 (2), 755–756. (31).
34.
DewarR. E.EllsJ. G.MundyG.Reaction time as an index of traffic sign perception. Human Factors, 1976, 18, 381–392. (32).
35.
EllingstadV. S.HeimstraN. W.Performance changes during the sustained operation of a complex psychomotor task. Ergonomics, 1970, 13, 693–705. (33).
36.
EllsJ. G.Analysis of temporal and attentional aspects of movement control. Journal of Experimental Psychology, 1973, 99, 10–21. (34).
37.
EnstromK. D.RouseW. B.Telling a computer how a human has allocated his attention between control and monitoring tasks. Proceedings of the Twelfth Annual Conference on Manual Control, University of Illinois, Urbana-Champaign, Illinois, NASA TMX-73, May, 1976, 170, 104–123. (N77-14746) (35).
38.
EphrathA. R.Pilot performance in zero-visibility precision approach. Unpublished doctoral dissertation, Massachusetts Institute of Technology, Cambridge, Massachusetts, Report No. NASA CR-137759, 1975, (36).
39.
EphrathA. R.A novel approach to the cross-adaptive auxiliary task. Proceedings of the Twelfth Annual Conference on Manual Control, University of Illinois, Urbana-Champaign, Illinois, NASA TMX-73, May, 1976, 170, 63–71. (N77–14746) (37).
40.
FigarolaT. R.BillingsC. E.Effects of meprobamate and hypoxia on psychomotor performance. Aerospace Medicine, 1966, 37, 951–954. (38).
41.
FinkelmanJ. M.GlassD. C.Reappraisal of the relationship between noise and human performance by means of a subsidiary task measure. Journal of Applied Psychology, 1970, 54, 211–213. (39).
42.
FisherS.The microstructure of dual-task interaction: I. The patterning of main task responses within secondary-task intervals. Perception, 1975, 4, 267–290. (a) (40).
43.
FisherS.The microstructure of dual-task interaction: II. The effect of task instructions on attentional allocation and a model of attention-switching. Perception, 1975, 4, 459–474. (b) (41).
44.
FleishmanE. A.The prediction of total task performance from prior practice on task components. Human Factors, 1965, 7, 18–27.
45.
FournierB. A.StagerP.Concurrent validation of a dual-task selection test. Journal of Applied Psychology, 1976, 61, 589–595. (42).
46.
GabayE.MerhavS. J.Identification of a parametric model of the human operator in closed-loop control tasks. IEEE Transactions on Systems, Man, and Cybernetics, 1977, 7, 284–292. (43).
47.
GabrielR. F.BurrowsA. A.Improving time-sharing performance of pilots through training. Human Factors, 1968, 10, 33–40. (44).
48.
GibsonH. B.CurranJ. D.The effect of distraction on a psychomotor task studied with reference to personality. Irish Journal of Psychology, 1974, 2 (3), 148–158. (45).
49.
GopherD.NorthR. A.The measurement of operator capacity by manipulation of dual-task demands. Savoy, Illinois: University of Illinois at Urbana-Champaign, Aviation Research Laboratory, Report No. ARL-74–21/AFOSR-74–15, October, 1974. (46).
50.
GopherD.NorthR. A.Manipulating the conditions of training in time-sharing performance. Human Factors, 1977, 19, 583–593.
51.
GopherD.WickensC. D.Tracking performance under time-sharing conditions with a digit processing task: A feedback control theory analysis. Proceedings of the Eleventh Annual Conference on Manual Control, NASA-Ames Research Center, NASA TMX-62, May, 1975, 464, 33–36. (N75-33678) (47).
52.
GouldJ. D.SchafferA.The effects of divided attention on visual monitoring of multi-channel displays. Human Factors, 1967, 9, 191–202. (48).
53.
GreenR.FluxR.Auditory communication and workload. AGARD Conference Preprint No. 216: Methods to Assess Workload. Cologne, Germany, AGARD-CPP-216, April, 1977, (A4)1–(A4)8. (49).
GundryA. J.Thresholds to roll motion in a flight simulator. Proceedings of the Visual and Motion Simulation Conference, Dayton, Ohio, American Institute of Aeronautics and Astronautics, April, 1976, 1–9. (51).
56.
HallT. J.PasseyG. E.MeighanT. W.Performance of vigilance and monitoring tasks as a function of workload. Marietta, Georgia: Lockheed-Georgia Company, Report No. AMRL-TR-65-22, March, 1965. (52).
57.
HartS. G.Time estimation as a secondary task to measure workload. Proceedings of the Eleventh Annual Conference on Manual Control, NASA-Ames Research Center, NASA TMX-62, May, 1975, 464, 64–77. (N75-33679) (53).
58.
HeimstraN. W.The effects of “stress fatigue” on performance in a simulated driving situation. Ergonomics, 1970, 13, 209–218. (54).
59.
HermanL. M.Study of the single channel hypothesis and input regulation within a continuous simultaneous task situation. Quarterly Journal of Experimental Psychology, 1965, 17, 37–46. (55).
60.
HessR. A.TeichgraberW. M.Error quantization effects in compensatory tracking tasks. IEEE Transactions on Systems, Man, and Cybernetics, 1974, 4, 343–349. (56).
61.
HilgendorfE. L.Information processing, practice and spare capacity. Australian Journal of Psychology, 1967, 19, 241–251. (57).
62.
HockeyG. R. J.Changes in attention allocation in a multicomponent task under loss of sleep. British Journal of Psychology, 1970, 61, 473–480. (58).
63.
HohmuthA. V.Vigilance performance in a bimodal task. Journal of Applied Psychology, 1970, 54, 520–525. (59).
64.
HosmanR. J. A. W.Pilot's tracking behaviour under additional workload. Delft, The Netherlands: Delft University of Technology, Department of Aeronautical Engineering, Report No. VTH-199, June, 1975. (N77-13657) (60).
65.
HuddlestonH. F.Personality and apparent operator capacity. Perceptual and Motor Skills, 1974, 38, 1189–1190 (61).
66.
HuddlestonH. F.WilsonR. V.An evaluation of the usefulness of four secondary tasks in assessing the effect of a lag in simulated aircraft dynamics. Ergonomics, 1971, 74, 371–380. (62).
67.
JenningsA. E.ChilesW. D.An investigation of time-sharing ability as a factor in complex performance. Oklahoma City, Oklahoma: FAA Civil Aeromedical Institute, Report No. FAA-AM-76-1, May, 1976. (63).
68.
JexH. R.JewellW. F.AllenR. W.Development of the dual-axis and cross-coupled critical tasks. Proceedings of the Eighth Annual Conference on Manual Control, University of Michigan, Ann Arbor, Michigan, May, 1972, 529–552. (N73-20028) (64).
69.
JohnsonE. M.Effects of extended practice on dual-task performance. Proceedings of the Convention of the American Psychological Association, 1970, 5 (1), 13–14. (65).
70.
JohnstonW. A.GreenbergS. N.FisherR. P.MartinD. W.Divided attention: A vehicle for monitoring memory processes. Journal of Experimental Psychology, 1970, 53, 164–171. (66).
71.
KahnemanD.Attention and effort. Englewood Cliffs, N. J.: Prentice-Hall, 1973.
72.
KahnemanD.BeattyJ.PollackI.Perceptual deficit during a mental task. Science, 1967, 157, 218–219. (67).
73.
KalsbeekJ. W. H.SykesR. N.Objective measurement of mental load. In SandersA. F. (Ed.) Attention and performance. Amsterdam: North-Holland, 1967. (68).
KennedyJ. P.Time-sharing effects on pilot tracking performance. Unpublished master's thesis. Naval Post-graduate School, Monterey, California, 1975. (AD-A0I6 378) (74).
80.
KerrB.Processing demands during mental operations. Memory and Cognition, 1973, 7, 401–412.
81.
KleinG. A.Effect of attentional demands on context utilization. Journal of Educational Psychology, 1976, 68, 25–31. (75).
82.
KnowlesW. B.Operator loading tasks. Human Factors, 1963, 5, 155–161.
83.
KnowlesW. B.RoseD. J.Manned lunar landing simulation. Paper presented at the IEEE national winter convention on military electronics, Los Angeles, California, 1963.
84.
KrolJ. P.Variations in ATC-workload as a function of variations in cockpit workload. Ergonomics, 1971, 74, 585–590. (76).
85.
KyriakidesK.LeventhalH. G.Some effects of infrasound on task performance. Journal of Sound and Vibration, 1977, 50, 369–388. (77).
86.
LaabsG. J.StagerP.Monitoring the information-processing demands of attention switching. Canadian Journal of Psychology, 1976, 30, (2), 47–54. (78).
87.
LewisR. E. F.de la RiviereW. D.SweeneyD. M.Dual versus solo pilot navigation in helicopters at low level. Ergonomics, 1968, 11, 145–155. (79).
88.
LindsayP. H.NormanD. A.Short-term retention during a simultaneous detection task. Perception and Psychophysics, 1969, 5 (4), 201–205. (80).
89.
LongJ.Effect of task difficulty on the division of attention between non-verbal signals: Independence or interaction?Quarterly Journal of Experimental Psychology, 1976, 28, 179–192. (81).
90.
LooperM.The effect of attention loading on the inhibition of choice reaction time to visual motion by concurrent rotary motion. Perception of Psychophysics, 1976, 20 (1), 80–84. (82).
91.
MandlerG.WordenP. E.Semantic processing without permanent storage. Journal of Experimental Psychology, 1973, 100, 277–283. (83).
92.
MartinD. W.Residual processing capacity during verbal organization in memory. Journal of Verbal Learning and Verbal Behavior, 1970, 9, 391–397. (84).
93.
MartinD. W.KellyR. T.Secondary task performance during directed forgetting. Journal of Experimental Psychology, 1974, 103, 1074–1079. (85).
94.
MastersJ. C.MesibovG. B.Distraction and originality in word associations. Journal of Verbal Learning and Verbal Behavior, 1968, 7, 1117–1119. (86).
95.
McDonaldL. B.EllisN. C.Stress threshold for drivers under various combinations of discrete and tracking workload. Proceedings of the Human Factors Society Nineteenth Meeting, Dallas, Texas, October, 1975, 488–493. (87).
96.
McGrathJ. J.Performance sharing in an audio-visual vigilance task. Human Factors, 1965, 3, 141–153. (88).
97.
McLeodP. D.Interference of “attend to and learn” tasks with tracking. Journal of Experimental Psychology, 1973, 99, 330–333. (89).
98.
MeisterD.Behavioral foundations of systems development. New York: Wiley, 1976.
99.
MichonJ. A.Tapping regularity as a measure of perceptual motor load. Ergonomics, 1966, 9, 401–412. (90).
MirchandaniP. B.An auditory display in a dual-axis tracking task. IEEE Transactions on Systems, Man, and Cybernetics, 1972, 2, 375–380. (92).
102.
MitsudaM.Effects of a subsidiary task on backward recall. Journal of Verbal Learning and Verbal Behavior, 1968, 7, 722–725. (93).
103.
MontyR. A.RubyW. J.Effects of added work load on compensatory tracking for maximum terrain following. Human Factors, 1965, 7, 207–214. (94).
104.
MorganB. B.Jr.AlluisiE. A.Effects of workload stress on skilled performance with a code transformation task. Proceedings of the 77th Annual Convention of the American Psychological Association, 1969, 4 (2), 753–754. (95).
105.
MoskowitzH.McGlothlinW.Effects of marihuana on auditory signal detection. Psychopharmacologia, 1974, 40 (2), 137–145. (96).
106.
MurdockB. B.Jr.Effects of a subsidiary task on short-term memory. British Journal of Psychology, 1965, 56, 413–419. (97).
107.
NagarajaB. K. RaoGriffinM. J.Secondary task performance of helicopter pilots during low-level flight. University of Southampton, Institute of Sound and Vibration Research, Report No. ISVR-TR-54, December, 1971. (N74-10103/1) (98).
108.
NobleM.TrumboD.The organization of skilled response. Organizational Behavior and Human Performance, 1967, 2, 1–25.
109.
NobleM.TrumboD.FowlerF.Further evidence on secondary task interference in tracking. Journal of Experimental Psychology, 1967, 73, 146–149. (99).
110.
NorthR. A.Task components and demands as factors in dual-task performance. Urbana, Illinois: University of Illinois at Urbana-Champaign, Aviation Research Laboratory, Report No. ARL-77-2/AFOSR-77–2, January, 1977. (AD-A038 634) (100).
111.
NorthR. A.GopherD.Measures of attention as predictors of flight performance. Human Factors, 1976, 18, 1–14. (101).
112.
O'DonnelR. D.Secondary task assessment of cognitive workload in alternative cockpit configurations. AGARD Proceedings on Higher Mental Functioning in Operational Environments, Ankara, Turkey, AGARD-CP-181, October, 1975. (AD-A025 663) (102).
113.
OlsonB. A.AndersonP. A.CliffordR. R.KingW. J.LovingerD. N.WolfJ. D.Display and control requirements study for a V/STOL tactical aircraft: Volume II. Appendices. Minneapolis, Minnesota: Honeywell, Inc., Report No. AFFDL-TR-66–114, December, 1966. (AD-807 698) (103).
PoultonE. C.Tracking skill and manual control. London: Academic Press, 1974.
116.
PriceD. L.The effects of certain gimbal orders on target acquisition and workload. Human Factors, 1975, 77, 571–576. (105).
117.
PutzV. R.RotheR.Peripheral signal detection and concurrent compensatory tracking. Journal of Motor Behavior, 1974, 6 (3), 155–163. (106).
118.
RankinJ. E.A comparison of visual cuing methods in large displays during performance of a secondary task. Unpublished master's thesis, Texas A&M University, College Station, Texas, 1971. (AD-747 688) (107).
119.
RolfeJ. M.The secondary task as a measure of mental load. In SingletonW. T.FoxJ. G.WhitfieldD. (Eds.) Measurement of man at work: An appraisal of physiological and psychological criteria in man-machine systems. London: Taylor & Francis, Ltd., 1971.
120.
RoschE.Secondary task for full flight simulation incorporating tasks that commonly cause pilot error: Time estimation. Berkeley, California: University of California, Report No. NASA-TM-X-74153, October, 1975. (N76-33846) (108).
121.
SalmoniA. W.The attention demands of input monitoring. Journal of Human Movement Studies, 1975, 7 (3), 143–148. (109).
122.
SandersM. G.SimmonsR. R.HofmannM. A.De-BonisJ. N.Visual workload of the copilot/navigator during terrain flight. Proceedings of the Human Factors Society Twenty-First Annual Meeting. San Francisco, California, October, 1977, 262–266. (110).
123.
SchoriT. R.A comparison of visual, auditory, and cutaneous tracking displays when divided attention is required to a cross-adaptive loading task. Ergonomics, 1973, 16, 153–158. (111).
124.
SendersJ. W.The estimation of operator workload in complex systems, In DeGreeneK. B. (Ed.) Systems Psychology. New York: McGraw-Hill, 1970.
125.
SharpE. D.Effects of primary task performance on response time to toggle switches in a workshop configuration. Wright-Patterson Air Force Base, Ohio: Aerospace Medical Research Laboratories, Report No. AMRL-TR-66-190, April, 1967. (AD-655 770) (112).
126.
ShulmanH. G.BriggsG. E.Studies of performance in complex aircrew tasks. Columbus, Ohio: Ohio State University Research Foundation, Report No. AFOSR-TR-72-01. December, 1971. (AD-735 762) (113).
127.
ShulmanH. G.GreenbergS. N.Perceptual deficit due to division of attention between memory and perception. Journal of Experimental Psychology, 1971, 88, 171–176. (114).
128.
ShulmanH. G.GreenbergS. N.MartinJ.Intertask delay as a parameter of perceptual deficit in divided attention. Journal of Experimental Psychology, 1971, 88, 439–440. (115).
129.
SiegelA. I.WilliamsA. R.Jr.Identification and measurement of intellective load carrying thresholds. Wayne, Pennsylvania: Applied Psychological Services, December, 1974. (116).
130.
SilversteinC.GlanzerM.Concurrent task in free recall: Differential effect of LTS and STS. Psychonomic Science, 1971, 22, 367–368. (117).
131.
SmithM. C.Effects of varying channel capacity on stimulus detection and discrimination. Journal of Experimental Psychology, 1969, 52, 520–526. (118).
132.
SmithR. L.LucacciniL. F.GrothH.LymanJ.Effects of anticipatory alerting signals and a compatible secondary task on vigilance performance. Journal of Applied Psychology, 1966, 50, 240–246. (119).
133.
SmithS.FarrellR. J.GonzalezB. K.Effects of control-display compatibility and monitoring cues on multiple-task performance. Perceptual and Motor Skills, 1965, 20, 781–785. (120).
134.
SolidayS. M.SchohanB.Task loading of pilots in simulated low-altitude high-speed flight. Human Factors, 1965, 7, 45–53. (121).
135.
SpykerD. A.StackhouseS. P.KhalafallaA. S.McLaneR. C.Development of techniques for measuring pilot workload. Roseville, Minnesota: Honeywell, Inc., Report No. NASA CR-1888, November, 1971. (N72-12060) (122).
136.
StagerP.ZufeltK.Dual-task method in determining load differences. Journal of Experimental Psychology, 1972, 94, 113–115. (123).
137.
StaplefordR. L.Comparisons of population subgroups' performance on a keyboard psychomotor task. Proceedings of the Ninth Annual Conference on Manual Control, Massachusetts Institute of Technology, Cambridge, Massachusetts, May, 1973, 245–255. (N75-19126) (124).
138.
StormW. F.HartmanB. O.IntanoG. P.PetersG. L.Endocrine-metabolic effects in short-duration, high-workload missions: Feasibility study. USAF School of Aerospace Medicine, Technical Report No. 76(30), August, 1976. (AD-AO30 524) (125).
139.
TicknerA. H.PoultonE. C.CopemanA. K.SimmondsD. C. V.Monitoring 16 television screens showing little movement. Ergonomics, 1972, 15, 279–291. (126).
140.
TruijensC. L.TrumboD. A.WagenaarW. A.Amphetamine and barbiturate effects on two tasks performed singly and in combination. Acta Psychologica, 1976, 40, 233–244. (127).
141.
TrumboD.MiloneF.Primary task performance as a function of encoding, retention, and recall in a secondary task. Journal of Experimental Psychology, 1971, 91, 273–279. (128).
142.
TrumboD.NobleM.Secondary task effects on serial verbal learning. Journal of Experimental Psychology, 1970, 85, 418–424. (129).
143.
TrumboD.NobleM.Response uncertainty in dual-task performance. Organizational Behavior and Human Performance, 1972, 7, 203–215. (130).
144.
TrumboD.NobleM.SwinkJ.Secondary task interference in the performance of tracking tasks. Journal of Experimental Psychology, 1967, 73, 232–240. (131).
145.
TylerD. M.HalcombC. G.Monitoring performance with a time-shared encoding task. Perceptual and Motor Skills, 1974, 38, 383–386. (132).
146.
VroonP. A.Tapping rate as a measure of expectancy in terms of response and attention limitation. Journal of Experimental Psychology, 1973, 101, 183–185. (133).
147.
WatsonB. L.The effect of secondary tasks on pilot describing functions in a compensatory tracking task. Ontario, Canada: Toronto University. Institute for Aerospace Studies, Report No. UTIAS-178, June, 1972. (N72-30118)(134).
148.
WempeT. E.BatyD. L.Human information processing rates during certain multiaxis tracking tasks with a concurrent auditory task. IEEE Transactions on Man-Machine Systems, 1968, MMS-9 (4), 129–138. (135).
149.
WestbrookC. B.AndersonR. O.PietrzakP. E.Handling qualities and pilot workload. Wright-Patterson Air Force Base, Ohio: Air Force Flight Dynamics Laboratory, Report No. AFFDL-FDCC-TM-66-5, September, 1966. (AD-655 340) (136).
150.
WickensC. D.The effects of divided attention on information processing in manual tracking. Journal of Experimental Psychology: Human Perception and Performance, 1976, 2, 1–13. (137).
151.
WickensC. D.GopherD.Control theory measures of tracking as indices of attention allocation strategies. Human Factors, 1977, 19, 349–365. (138).
152.
WiegandD.Quantitative measurement of psychological stress while driving by means of a simultaneous secondary task. Zeitschrift für Experimentelle und Angewandte Psychologie, 1974, 21 (4), 679–690. (139).
153.
WienerE. L.On simultaneous monitoring and tracking. Journal of Applied Psychology, 1975, 60, 100–105. (140).
154.
WierwilleW. W.GutmannJ. C.Comparison of primary and secondary task measures as a function of simulated vehicle dynamics and driving conditions. Human Factors, 1978, 20, 233–244. (141).
155.
WierwilleW. W.WilligesR. C.Survey and analyses of operator workload assessment techniques. Blacksburg, Virginia, Systemetrics, Inc., Report No. S-78–101. September, 1978.
156.
WrightP.HollowayC. M.AldrichA. R.Attending to visual or auditory verbal information while performing other concunent tasks. Quarterly Journal of Experimental Psychology, 1974, 26, 454–463. (142).
157.
ZaitzeffL. P.Aircrew task loading in the Boeing multimission simulator. Proceedings of the 56th AGARD Conference on Measurement of Aircrew Performance, Brooks Air Force Base, Texas, May, 1969, (8)1-(8)3. (143).
158.
ZeitlinL. R.FinkelmanJ. M.Research note: Subsidiary task techniques of digit generation and digit recall as indirect measures of operator loading. Human Factors, 1975, 77, 218–220. (144).
