Spatial Ability and Individual Differences in the Use of

Perceptually Shaded Slope Maps

Thomas J. Pingel1, Nicole D. LaDue2, and Sheldon P. Turner2

1Department of Geography, 2Department of GeologyNorthern Illinois University

21-25 April 2015 2015 Annual Meeting of the Association of American Geographers

Chicago, IL

1

2

Perceptually Shaded Slope Maps (PSSMs)

• Slope is exaggerated, then mapped to graytone

• Resulting appearance looks hand-drawn, which speaks to its efficacy as a visualization

• Offers a higher contrast image than hillshade, with better affordance for color overlay

• Most appropriate for mixed urban environments

PSSM of ancient Maya site at El Pilar

PSSMs are based on the idea of “cognitive slope.”

People exaggerate the vertical component of slope by a factor of 2.3x.

3(Pingel 2010, following Proffitt et al. 1995)

4

A vertical exaggeration of 2.3x maps graytone to slope in a manner similar to previous work.

lum

inou

s in

tens

ity

slope (deg)

5

Initial results (Pingel and Clarke, 2014) demonstrated overall efficacy of the PSSM compared to other

representations, but there were hints of significant individual differences.

Is the PSSM good for everyone?

How does visualization type interact with sex and spatial ability?

6

“Spatial Ability”

From Hegarty et al. (2006), Wolbers and Hegarty (2010)

7

• Gilmartin and Patton (1984)– Sex differences in thematic map reading are largest in young children– Men are better able to “visualize” spatial text– But the kind of map affects the degree to which females benefit from maps-

with-text (w/Gilmartin 1987)• Chang and Antes (1987)

– Men perform better on topographic map reading, but not tests involving road maps

– But culture mediates the relationship• Liben, Myers, and Kastens (2008)

– No difference in accuracy in plan vs oblique views on a mark-your-location test– Spatial tasks did predict performance, but the specific spatial skills that

predicted success differed– “… our data do not yet permit firm conclusions about the way that map

qualities interact with environmental and person qualities…”• Uttal et al. (2013)

– Many sex and spatial ability differences in map reading tasks can be remediated by training

8

Methods (1)

• Previous work demonstrated potential of the technique– Pingel & Clarke (2014)– Compared to hillshade, orthophoto,

hypsometric tinting

• Goals– PSSM vs. Hillshade– Response time and accuracy on

representative map use tasks– Interactions of presentation type

and • Sex• Spatial ability

9

Methods (2)• Tasks

– Profile estimation & Map Rotation– Perspective Taking (Kozhevnikov & Hegarty 2001) – Card Rotation – Reponses indicated with touch screen

• 177 participants– 48% male– Drawn from introductory geography courses

• Non-results– Men reported significantly more experience with geography and

topographic maps, but both measures were uncorrelated with performance

– SBSOD (Hegarty et al. 2002) was uncorrelated with performance

10

Profile estimation(Hillshade vs. PSSM)

Identify the correct transect from among three alternatives.

11

Map Rotation(Hillshade vs. PSSM)

Rotation… or rotation + reflection?

12

Perspective Taking

Imagine that you are at the stop sign, and facing the house. Point to the traffic light.

13

Card RotationRotation, or rotation + reflection?

RTs were similar for profile estimation and perspective taking; map and card rotation were much faster.

Perspective Taking Profile Estimation Map Rotation Card Rotation0

2

4

6

8

10

12

14

16

Per Item Response Time (s)

14

15

Domain and task type interact.

Similar domains are more related, and similar task types are more related.

Task Correlations (RT)

Map Rotation

Profile Estimation Perspective Taking

Card Rotation

.62

.39

.36

.34

.68

.44

16

t(17

6)=1

.75,

p=0

.08

t(176)=4.58, p<0.001

PSSMs showed improved mean accuracy rate and response time on the Profile Estimation task.

17

t(175)=1.16, p=0.25

t(17

5)=3

.08,

p=0

.002PSSMs showed

improved accuracy rates on the Map Rotation

task, but no significant improvement on response time.

18

Of the 4 tasks, only perspective taking showed significant sex differences.

*response time: t(174)=1.77, p=0.08; mean angular error: t(174)=4.57, p<0.001

19

A metric of spatial ability was calculated from a linear composite of aligned z-scores of response time and accuracy rate for

perspective taking and card reading tasks.

Cohen’s d: 0.47; t(175)=3.23, p=0.002

20

Profile EstimationMarginal GLM main effect for sex on response time

β=-.89, t(172)=1.70, p=.09%

cor

rect

response time (s)

21

Map RotationInteraction between sex and spatial ability on accuracy

β=-.08, t(172)=1.99, p=.049%

cor

rect

response time (s)

22

We are currently conducting an eye-tracking study to determine how and why PSSMs support increased

response times and accuracy rates.

23

Acknowledgments

• Illinois Geographical Society Research Grant– Ben Maloney

• NIU Undergraduate Research Assistantship Program– Stacey Terlep, James Huske, and Stephanie Clark