Eye Movement Strategies In Navigational Tasks

Austin Ducworth

Melissa Falzetta

Lindsay Hyma

Katie Kimble

James Michalak

Introduction

Navigation involves keeping track of one’s current location and planning routes to new destinations.

Maps are the most common navigational tool.

Coordinating reference frames is a key difficulty in navigational tasks

Individual Differences

Cardinal Direction Tasks

Prove to be more difficult than other navigational tasks

Prone to show wide individual differences in performance

Set-Up

Started w/ Dr. D’s GCI++ code.Removed the pre-defined duration within

the scenario (.tri) file.Checked for a key press event for the

operator to switch between images.Modify the margins so the 640x299 and

350x340 images were centered within the 640x480 display window.

Analysis

Objective: We wanted to turn the raw coordinate and time data into interpretable output.

Problem: The analysis program included in Dr. D’s gci++ code overlaid the scanpath over the image, however, it did not show the eye movements in sequence

ANALYSIS Approach

Approach: Write a java application to read in por data and write the sequence of roi hits for each image.

ANALYSIS 1st Attempt• Parse through the por data and determine if the coordinate represent a point within pre-defined ROIs.

• If a point lies within an ROI, a hit and the duration is recorded in an output file.

• PROBLEMS:• Defining ROIs• Calibration• Inconclusive Results

ANALYSIS 2nd Attempt• Divide all points within the image into a grid of user specified proportions.

• PROBLEMS:• Data Analysis Lengthy• Not Enough Testing

Sample Output

ANALYSIS 3rd Attempt

• Analyze the scanpath using the analysis program.

• PROBLEMS:• Sequence must be guestimated

• ADVANTAGES:• Quick Analysis• Previously Tested Results• Ass Saving Technology

Experiment

Between subjects design2 strategies

Heading reference strategy 3D First strategy

8 participants (4 per condition) Excluding 1 participant for failure to follow

instructions

Design

Initial trainingStrategy training24 practice trialsEye movement trials

Strategy Training

Eye Movement Trials

Individual map

Table knock

Answer Screen

AnalysisEach scanpath was superimposed on its

respective mapAnalyzed eye movementsLooked for expected patterns to emerge

Analysis: Expected Patterns3D First

First look at region 12 and then to the parking lot with the cars (regions 16 or 17) to form an angle.

Then Transpose that angle to the right side of the map, mentally rotate the angle to coincide with the heading direction of the airplane (regions 15 and 20).

Heading ReferenceFirst expected to look at regions corresponding to the map arrow (regions 15 and 20) Then look at regions 2,7.or 12 to orient themselves on the 3D map. They look to the left and right of these regions (regions 6,11 and 7) to determine the direction of these parking lots

Heading Ref.

3D First

Performance Results

Heading reference: 76.4% correct3-D First: 66.7% correctNot a notable performance difference between

strategiesPerformance Based on Strategy

18

20

22

24

26

1 2 3 4

Participant

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HeadingReferencing3-D First

Strategy Use Results

Heading Referencing: used strategy on 50% of trials.

3-D First: used strategy on 74% of the trials.

One sample t-test: a significant number of participants did not use the strategy

Qualitative Observations

Some subjects did not have eye movements over the arrow showing airplane direction.

3-D First strategy: Some subjects exhibited a visual angle formation in their scanpaths while others may have been forming an angle mentally rather than via eye movements

Discussion

Did not show a significant difference in performance depending on strategy used

Did not use strategy taught a significant percentage of time

Recommendations

Use a more objective strategy for data analysis

Use less training: more mistakes may give more insight into a superior strategy

Use more sensitive measures: response time

Questions??