Performance Operating Characteristics for Spatial and Temporal Discriminations: Common or Separate Capacities? J. E. Thropp, J. L. Szalma, and P. A. Hancock University of Central Florida Contact J. E. Thropp: j_thropp@hotmail.com

Tasks as Stressors Performance tasks are the proximal sources of stress (Hancock & Warm, 1989) Two task dimensions: Information structure Information rate

PHYSIOLOGICAL ADAPTABILITY PSYCHOLOGICAL ADAPTABILITY Physiological Zone of Maximal Adaptability Maximal Minimal Psychological Zone of Maximal Adaptability Dynamic Instability Dynamic Instability COMFORT ZONE PHYSIOLOGICAL ADAPTABILITY (ATTENTIONAL RESOURCE CAPACITY) PSYCHOLOGICAL ADAPTABILITY NORMATIVE ZONE Minimal Maximal Hypostress Hyperstress STRESS LEVEL

Tasks as Stressors

Spatial and Temporal Processing: Common Resource Capacity? Resources Resources Likewise, if spatial and temporal properties share resources, resources will have to be shared between them. Spatial Temporal Spatial Attentional narrowing may occur as a result of decreasing resources

Testing Resource Sharing Constructing Performance Operating Characteristics (POCs: Navon & Gopher, 1979) Dual-task methodology

Performance Operating Characteristics (POCs) 90% Temporal 10% Spatial 100% Temporal 0% Spatial 50% Temporal 50% Spatial 90% Spatial 10% Temporal 100% Spatial 0% Temporal

Experimental Participants Six participants (3 males, 3 females) Age range 18-24; mean age = 20 Each participant completed 480 trials for each of 10 conditions

ATTENTIONAL ALLOCATION STIMULI ATTENTIONAL ALLOCATION Spatial Temporal Spatial 100% 0% Baseline Temporal 90% 10% Easy 50% 50% Dual-Task 10% 90% 32 mm 35 mm 300 ms 450 ms Neutral Critical Neutral Critical 0% 100% Baseline 100% 0% Baseline 33.5 mm 32 mm Neutral Critical 300 ms Spatial Temporal 90% 10% Dif. 50% 50% Dual-Task 10% 90% 360 ms Critical 0% 100% Baseline

Days 2, 3, and 4 Day 1 Practice (two-alternative forced choice) 90% Spatial – 10% Temporal (Easy) 90% Spatial – 10% Temporal (Difficult) 50% Spatial – 50% Temporal (Easy) 10% Spatial – 90% Temporal (Easy) 10% Spatial – 90% Temporal (Difficult) Day 1 Practice (two-alternative forced choice) Spatial Baseline (Easy) Spatial Baseline (Difficult) Temporal Baseline (Easy) Temporal Baseline (Difficult)

Dual-Task Spatial-Temporal Task Demonstration

READY What was the height of the line you just saw? 1 – Definitely short 2 – Possibly short 3 – Possibly long 4 – Definitely long What was the time of the line you just saw? 1 – Definitely short 2 – Possibly short 3 – Possibly long 4 – Definitely long READY

Results Sensitivity scores computed for each participant from POC curves Derived from ratings data Maximum likelihood procedures (MacMillan & Creelman, 1991)

Average Perceptual Sensitivity Temporal discrimination (d’) Spatial discrimination (d’)

Average Perceptual Sensitivity Temporal discrimination (d’) Spatial discrimination (d’)

Performance Operating Characteristics Participant 1 - FEMALE Participant 4 - FEMALE Temporal discrimination (d’) Temporal discrimination (d’) Spatial discrimination (d’) Spatial discrimination (d’) Participant 5 - FEMALE Participant 6 - MALE Temporal discrimination (d’) Temporal discrimination (d’) Spatial discrimination (d’) Spatial discrimination (d’)

Attentional Allocation Failures? Participant 2 - MALE Participant 3 - MALE Temporal discrimination (d’) Temporal discrimination (d’) 90tE 100tH 90sD 50-50E 90sE 100sD 100sE 100sH 90sE 90sE 90tD Spatial discrimination (d’) Spatial discrimination (d’)

Average POCs by Gender Averages Across Females Averages Across Males Temporal discrimination (d’) Temporal discrimination (d’) Spatial discrimination (d’) Spatial discrimination (d’)

Task-specific individual differences Likely that task-specific individual differences determine differences among participants Spatial vs. temporal Easy vs. difficult Time-sharing Limited evidence for general time-sharing ability (Wickens, Mountford, & Scheriner, 1981)

Relevant ID Variables Time sharing ability Ability to consciously control one’s allocation of attention (c.f., Derryberry & Reed, 2001) Ability to do spatial discrimination Ability to do temporal discrimination Extraversion

Tasks as Stressors

Future research Identify individual differences relevant to spatial and visual information Results indicate need for individual differences approach to POC studies to understand effects of manipulation of attention allocation and task difficulty Stress effects

References Braida, L. D. & Durlach, N. I. (1972). Intensity Perception II. Resolution in one-interval paradigms. Journal of the Acoustical Society of America, 51, 483-502. Derryberry, D., & Reed, M.A. (2001). A multidisciplinary perspective on attentional control. In C.L. Folk and B.S. Gibson (Eds.), Attraction, distraction, and action. Amsterdam: Elsevier. Easterbrook, J. A. (1959). The effect of motion on cue utilization and the organization of behavior. Psychological Review, 66, 183-201. Green, D. & Swets, J. (1966). Signal detection theory and psychophysics. New York: Wiley. Grondin, S. & Macar, F. (1992). Dividing attention between temporal and nontemporal tasks: A performance operating characteristic POC analysis. In F. Macar, V. Pouthas, and W. Friedman (Eds.) Time, Action, and Cognition: Towards bridging the gap. Dordrecht, Netherlands: Kluwer Academic. Hancock. P. A. & Warm, J. S. (1989). A dynamic model of stress and sustained attention. Human Factors, 31(5), 519-537. Hancock, P. A. & Weaver, J. L. (in press). On distortion under time stress. Theoretical Issues in Ergonomic Science. MacMillan, N.A., & Creelman, C.D. (1991). Detection Theory: A User's Guide. Cambridge: Cambridge University Press. Navon, D. & Gopher, D. (1979). On the economy of the human-processing system. Psychological Review, 86, 214-255. Wickens, C. D., Mountford, S. J., & Schreiner, W. (1981). Multiple resources, task-hemispheric integrity, and individual differences in time-sharing. Human Factors, 23(2), 211-229.

Contact J. E. Thropp: j_thropp@hotmail.com ACKNOWLEDGEMENT This work was supported in part by the Department of Defense Multidisciplinary University Research Initiative (MURI) program administered by the Army Research Office under Grant DAAD19-01-1-0621. P.A. Hancock, Principal Investigator. The views expressed in this work are those of the authors and do not necessarily reflect official Army policy. The authors wish to thank Dr. Sherry Tove, Dr. Elmar Schmeisser, and Dr. Mike Drillings for providing administrative and technical direction for the Grant. Contact J. E. Thropp: j_thropp@hotmail.com

Participant 1 Easy Hard 100se 100te p=.1564 100sh 100th p=.5797 100se 90se p=.0109** 100sh 90sh p=.2297 90se 50se p=.0141** 90sh 50sh p=.9370 50se 10se 50sh 10sh p=.0143** 10se 100te 10sh 100th 100te 90te p=.1596 100th 90th p=.2498 90te 50te p=.4036 90th 50th p=.2638 50te 10te p=.0001** 50th 10th p=.1619 10te 100se p=.2223 10th 100sh p=.0012**

Participant 2 Easy Hard 100se 100te p=.0000*** 100sh 100th 90se 10te 100se 90se p=.5364 100sh 90sh p=.5892 90se 50se p=.1836 90sh 50sh p=.0925 50se 10se p=.7835 50sh 10sh p=.3385 10se 100te 10sh 100th 100te 90te p=.3496 100th 90th p=.0872 90te 50te p=.0003** 90th 50th p=.7115 50te 10te p=.6682 50th 10th p=.7195 10te 100se p=.0195** 10th 100sh p=.0299**

Participant 3 Easy Hard 100se 100te p=.2009 100sh 100th p=.0743 100se 90se p=.0000*** 100sh 90sh p=.3610 90se 50se p=.0839 90sh 50sh p=.2310 50se 10se p=.7133 50sh 10sh p=.6557 10se 100te p=.0001** 10sh 100th p=.7173 100te 90te p=.0021** 100th 90th 90te 50te p=.1860 90th 50th p=.3038 50te 10te p=.8273 50th 10th p=.9687 10te 100se 10th 100sh p=.1006

Participant 4 Easy Hard 100se 100te p=.0033** 100sh 100th p=.0114** 100se 90se 100sh 90sh p=.4602 90se 50se p=.2017 90sh 50sh p=.0571 50se 10se 50sh 10sh 10se 100te 10sh 100th p= 100te 90te p=.1023 100th 90th p=.0001** 90te 50te p=.9875 90th 50th p=.3936 50te 10te 50th 10th p=.0741 10te 100se 10th 100sh

Participant 5 Easy Hard 100se 100te p=.0000*** 100sh 100th p=.7564 100se 90se p=.0681 100sh 90sh p=.7210 90se 50se p=.2047 90sh 50sh p=.1971 50se 10se p=.0050** 50sh 10sh p=.1830 10se 100te 10sh 100th p= 100te 90te 100th 90th p=.2127 90te 50te p=.0004** 90th 50th p=.1422 50te 10te p=.0001** 50th 10th 10te 100se 10th 100sh

Participant 6 Easy Hard 100se 100te p=.0072** 100sh 100th p=.8869 100se 90se p=.0326* 100sh 90sh p=.9388 90se 50se p=.2024 90sh 50sh p=.2442 50se 10se p=.0259* 50sh 10sh p=.9818 10se 100te 10sh 100th p= 100te 90te p=.5677 100th 90th p=.1299 90te 50te p=.2784 90th 50th p=.1440 50te 10te p=.7658 50th 10th p=.8193 10te 100se 10th 100sh

Performance Operating Characteristics Participant 1 Participant 6 Participant 5 Participant 4 Temporal d’ Temporal d’ Spatial d’ Temporal d’ Temporal d’ Spatial d’

Attentional Allocation Failures? Participant 2 Participant 3 Temporal d’ Temporal d’ Spatial d’ Spatial d’

Acknowledgement This work was supported in part by the Department of Defense Multidisciplinary University Research Initiative (MURI) program, P. A. Hancock, Principal Investigator, administered by the Army Research Office under grant DAAD19-01-1-0621. The views expressed in this work are those of the authors and do not necessarily reflect official Army policy. The authors wish to thank Dr. Sherry Tove, Dr. Elmar Schmeisser, and Dr. Mike Drillings for providing administrative and technical direction for the grant.

Experimental Participants Six participants (3 males, 3 females) Age range 18-24; mean age = 20 480 trials for each of 10 conditions) to achieve stable SDT estimates (Green & Swets, 1966)

Discussion POC curve averaged across participants indicates partial tradeoff Spatial task more vulnerable to attention allocation manipulation Sacrificing attention to spatial task does not improve temporal task above 50-50 condition Shape of easy condition POC curve indicates spatial task may draw on resources shared with temporal task temporal task draws on separate resource pool

Performance Operating Characteristics Participant 1 Participant 6 Participant 5 Participant 4 Temporal d’ Temporal d’ Spatial d’ Temporal d’ Temporal d’ Spatial d’

Possible evidence for resource- sharing Spatial and temporal processing may share resources Spatial-temporal tradeoff in averaged POC Tradeoff observed only in participants 1 and 4 Resource-sharing may be an individual difference and task-dependent

Hancock and Warm (1989) Rate and structure may be oblique Angles may vary among individuals Individual differences could be another dimension