What coordinate system does RatBat use?
How do the tasks position objects on the screen?
All RatBat tasks treat the screen as if it were a 1000x750 grid. They divide the screen up into rectangles, shown below. When called upon to display a stimulus, they attempt to work out the stimulus size and then they try to position the stimulus in the centre of the grid square tha they are using, assuming that the stimulus begins at (0,0) in its internal coordinate system (the system with which you define objects).
The tasks will have problems determining the size of text, and of bitmaps if you don't force the bitmap to a specified size. You should therefore test these stimuli before using them.
| • | Reinforcement Familiarization doesn't display any stimuli. |
| • | Touch Training uses the two-way grid. |
| • | Reversal Learning uses the two-way grid for two-stimulus tasks, and the middle row of the nine-way grid for three-stimulus tasks. |
| • | Delayed Matching/Non-matching To Sample uses the nine-way grid (location 4 for the presentation phase, and locations 0, 2, 6, and 8 for the choice phase). |
| • | Paired-Associates Learning uses the nine-way grid. |
| • | Simple Schedules of Reinforcement uses the centre of the nine-way grid. |
| • | N-Pair Concurrent Visual Discrimination uses the two-way grid. |
The sizes of these grids are shown below. In the 16-, 9-, and 4-way grids, the space between the grid squares and between the grid and the edge of the screen is 5% of the screen's extent. Refer to the width/height of individual cells; for example, stimuli designed for use with tasks that use the nine-way grid should fit in a 267x200 rectangle. Not all the grids shown below are used at present.
