Variants · VR
VR data and analysis
From raw trial files to the methods section.
Virtual trials produce rich data: position, heading and timing. These questions cover where it goes, what to keep, and how to analyse and report it.
VR water maze measures
VR trials are analysed with ‘Morris Water Maze’ > ‘ANALYZE’, just like the water maze, so the same measures are read in the same way. Quad1 is NE, Quad2 SE, Quad3 SW and Quad4 NW, matching the video tracking order.
More detail
HVS 6D VR records time-stamped positions at a variable rate; HVS Image smooths these to one position per 100 ms (10 Hz), stored in the .hvs and used for all measures. Active speed uses only intervals at or above the inactivity threshold (default 0.05 m/s, adjustable).
For the VR water maze, a diameter of 200 (cm) is recommended so results are comparable with the rodent maze; keep it consistent across experiments. Rodent and human VR inactivity values should not be compared directly. Cite the HVS vrScript technical reference (doi:10.5281/zenodo.22303968) and the inactivity documentation (doi:10.5281/zenodo.21797205).
Reading HVS 6D VR water maze results
VR trials are analysed just like the water maze, so the same measures and cautions apply. Rodent and human VR values should not be compared directly.
- Typical control pattern
- No VR-specific control pattern is verified yet, so read results as for the water maze: quadrant measures are only meaningful when targets sit at quadrant centres; otherwise use close encounters and Gallagher proximity.
- Signs of impairment
- When humans are required to use spatial cues to navigate to a hidden escape platform, patients with hippocampus resections display severe impairments in spatial navigation relative to age-matched controls (Astur et al., 2002).
- Signs of strong memory
- No published pattern has been confirmed for this test yet, so compare with your own control group.
Set-up problems that look like results
- Movement continues after the participant stops: shorten SMOOTH_MOTION; if small vibrations or sounds move the participant, lower OMNI_SENS a little.
- Light steps are missed: raise OMNI_SENS.
More detail
VR analysis shows only the platform position used for the trial. Probe trials run to the maximum time even when the target is reached, so keep the learned position in TARGET_POSITION so it is shown on plots and analysed. HVS 6D VR does not record experimenter assistance, so note any help you gave.
Astur et al. (1998) consistently found that males navigate to the hidden platform better than females across a variety of measures. Thornberry et al. (2021) report an inconsistency of use of the virtual water maze, particularly with respect to the environmental setup and procedures, so report your environment and cues in full.
Questions people ask
Where are VR trial data saved, and why can't I see my new trials?
Every trial is saved automatically as a JSON .BOND file plus an .hvs file; after an upgrade new trials can appear at the top of the list. 1) Check Data_File_Location.txt for the BOND location. 2) Look at the top of the list, or sort the HVS folder by date. 3) Move older files to a subfolder if helpful (put them back to analyse together).
More detail
Time-stamped position data and all settings are saved in a JSON .BOND file at the location given in C:\Users\User\AppData\LocalLow\HVS Image Software Ltd\HVS 4D VR\Data_File_Location.txt; the BOND folder sits in the same Data folder as HVS (e.g. …\Data\Morris Water Maze\HVS). After an upgrade file numbering restarts, so new trials appear near the top of the analysis list. Sorting by date in File Explorer and moving older files into a subfolder helps. Unwanted test files can be moved or deleted without affecting numbering.
Going deeper
If Data_File_Location.txt is missing, contact HVS so the trials can be moved to the right folder. Heart-rate and EEG data are in subfolders of BOND. Outputs include .hvs/.sum (text, CSV, SPSS, Excel) and .bond (JSON).
Which VR files must I keep and back up?
Keep and back up both the .BOND and .hvs files: they are your raw data. 1) Keep .sum files to make new CSTs. 2) Keep .hvs files to make new .sum files. 3) Keep .BOND files, since corrected .hvs files can be regenerated from them. 4) Ask HVS about automatic back-ups.
More detail
You can make new results files with different variables as long as you keep .sum files (or .hvs files to remake them), and new .sum files with different trial sets as long as you keep .hvs files. .BOND and .hvs are raw data: always back them up and keep them after exporting results. HVS can advise on automatic back-ups.
Going deeper
The .BOND file holds every time-stamped position and setting, so HVS can regenerate a corrected .hvs file from it if one is ever damaged or analysed wrongly. That is why BOND files matter most.
How do I analyse VR water maze or target-finding trials?
VR trials are analysed with 'Morris Water Maze' > 'ANALYZE', just like the water maze. 1) Double-click a trial for its plot, then 'OK' for the summary; 'Full Analysis' shows everything. 2) For batches, highlight trials, name your SUM file and click 'Analyze Batch or Series'. 3) 'Export Results / Setup Custom' > highlight the SUM > '2. Define' > pick variables > 'Save' > '3. Make Custom Results File'. 4) Open the CST in Excel.
More detail
Click 'Morris Water Maze', then 'ANALYZE' (ignore other buttons). Double-click a trial to view its plot, then 'OK' for the summary; 'Full Analysis' shows and saves all measures. 'Advanced' lets you add analyses and change values such as counter size; repeating with different values can reveal effects. For batches, highlight trials, type a name in 'Name your Summary (SUM) file' and press Enter or click 'Analyze Batch or Series'. Then click 'Export Results / Setup Custom', highlight the SUM, click '2. Define', choose variables (they move to the right), 'Save', then '3. Make Custom Results File'. CST files are comma-separated (save as .csv or import into Excel), in …\Data\Morris Water Maze\CST.
Going deeper
VR analysis shows only the platform position used for the trial (ask HVS for additional positions or use location_of_interest). Corrected .hvs files can always be regenerated from the .BOND raw data.
What technical details should I report for HVS 6D VR in a methods section?
Report the versions, your vrScript settings and the analysis definitions. 1) Analysis version is on the right of the HVS Image main menu. 2) HVS 6D VR records time-stamped positions; HVS Image smooths to one position per 100 ms. 3) Active speed uses only intervals at or above the inactivity threshold (default 0.05 m/s). 4) Cite the vrScript reference DOI 10.5281/zenodo.22303968.
More detail
HVS 6D VR records time-stamped positions at a variable rate (about 68/s in one example); HVS Image smooths these to one position per 100 ms (10 Hz), stored in the .hvs and used for all measures. Active speed = Euclidean distance between successive smoothed positions / elapsed time, using only intervals at or above the inactivity threshold (default 0.05 m/s, adjustable; exactly 0.05 counts as active). Start positions and orientation are defined per trial in the vrScript and recorded in .BOND headers. HVS 6D VR does not record experimenter assistance (scripted audio is possible). The vrScript files and BOND headers are the best configuration record.
Going deeper
Cite the HVS vrScript technical reference (DOI 10.5281/zenodo.22303968) and the inactivity documentation (DOI 10.5281/zenodo.21797205). Corrected Gallagher global (CGPROXmt): theoretical time t = d0 / v_active; exclude floor(t × f) samples; mean of the remaining distances; N/A if no active speed or samples; slices are referenced to trial start.
How are VR coordinates mapped to quadrants (NE, SE, SW, NW)?
Quadrant boundaries pass through the pool centre: Quad1 = NE, Quad2 = SE, Quad3 = SW, Quad4 = NW. 1) NE is positive x and positive z. 2) SE is +x, -z; SW is -x, -z; NW is -x, +z.
More detail
In VR analysis the horizontal axis is z = 0 and the vertical x = 0, both through the centre. NE = x+ z+; SE = x+ z-; SW = x- z-; NW = x- z+. Quad1 NE, Quad2 SE, Quad3 SW, Quad4 NW, matching the video tracking order (starting NE, clockwise).
Going deeper
Quadrant measures are only meaningful when targets sit at quadrant centres; otherwise use close encounters and Gallagher proximity.
A related VR task with its own measures is the triangle completion (return-to-home) task.
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