School of Psychology and Clinical Language Sciences

Model:

A simple linear mapping between S and est provides a reasonable

prediction of the data (see above). Note that the mapping is different for the red-yellow boxes than the blue-pink boxes but in each case is the same for all three viewing zones.

References 1. Gilson, S. J., Fitzgibbon, A. W., and Glennerster, A. (2008). Spatial calibration of an optical see-through head-mounted display. Journal of Neuroscience Methods, 173(1):pp.140–

146 2. Gilson, S. J., Fitzgibbon, A. W., and Glennerster, A. (2011). An automated calibration method for non-see-through head mounted displays. Journal of Neuroscience Methods,

199(2):pp.328–335 3. Vuong, J., Pickup, L.C., and Glennerster, A. (2013). The effect of walking and teleportation on spatial updating in virtual and real scenes. i-Perception 2013, Volume 4, Issue 7; Talk:

The Scottish Vision Group Conference 2013, Glencoe, Scotland 4. Waller, D. (2004). Using virtual environments to assess directional knowledge. Journal of Environmental Psychology, 24(1):pp.105-116. 5. Richardson, A. E., Montello, D. R., and Hegarty, M. (1999). Spatial knowledge acquisition from maps and from navigation in real and virtual environments. Memory &

cognition,27(4):pp.741-50.

Large systematic biases in pointing to real and virtual unseen targets

Question: Are there systematic biases as we point to unseen targets?

Methods: Spatially calibrated head mounted display nVis SX111, see [1,2]; Vicon real-time optical tracking system, 7 MX3 and 7 T20S cameras; 60Hz display, end-to-end latency 33 ms.

Task: Interval 1:

1. Remember all four target boxes at start zone .

2. Walk to viewing zone a , b , or c .

Interval 2:

1. Face a poster on the wall, indicating the colour of the

next target.

2. Use hand-held pointer to shoot each box.

Question: Can we predict these

biases?

Interval 1: Interval 2: Direct Path (in VR only):

− Screen

disappeared

when

leaving start

zone.

− Screen

reappeared

when zone

b/c entered.

Different facing directions (in VR only):

− As soon as

participant

entered zone a/c,

poster appeared

either North,

South or West of

the zone.

− Poster indicated

target box.

• 8 Participants, 9 box layouts, 3 viewing zones. Repeated in real and virtual environment. Direct and indirect walking only in VR. Participant shot 32 times in a random order to all the boxes (not visible at this point). In total, 1728 pointing samples per participant.

• 8 Participants, 9 box layouts, 3 viewing zones. Repeated in real and virtual environment. Direct and indirect walking only in VR. Participant shot 32 times in a random order to all the boxes (not visible at this point). In total, 768 pointing samples per participant.

• 7 Participants; 6 box layouts; 2 viewing zones; 864 pointing samples per participant; Participant shot 26 times in a random order to all the boxes not visible at this point.

Large biases that persist in virtual and real world stimuli (R2 = 0.88, p < 0.001), see [3,4,5].

Large biases that persist in direct and indirect walking (R2 = 0.94, p < 0.001).

Positive or negative biases depending on the shooting zones.

Large biases that persist in different facing directions (R2 = 0.96, p < 0.001).

Each symbol is a mean across 20 participants. Colour indicates box colour.

Each symbol is a mean across 7 participants. Colour indicates box colour.

Conclusions: o Participants show large, systematic

biases o Simple gain-based model predicts data

better than true geometry

Data:

Data: Model:

Parameters:

Ground Truth:

For more details and raw data, please visit: www.jennyvuong.net

S [metre]:

true [degree]:

est [degree]:

S

true est

Shooting direction

pred pred

• 7 Participants, 6 box layouts, 2 viewing zones, 3 facing directions. In virtual environment only. Participant shot 32 times in a random order to all the boxes (not visible at this point). In total, 864 pointing samples per participant.

Jenny Vuong | Lyndsey C Pickup | Andrew W Fitzgibbon | Andrew Glennerster http://www.reading.ac.uk/3DVision | http://www.jennyvuong.net

Poster locations (one

location per trial)