An adjuster and response handler element that lets the subject adjust properties of other elements by clicking and dragging the mouse cursor on screen like a slider. Or you can use property move to adjust the position of another element by clicking and dragging the element. One mouse button adjusts and the other says "done adjusting". By default waits for one "done adjusting" response, then ends on its own (so you don't need to set property end unless you want it to end earlier). Response values generated are adjusted property value(s). Note mouseAdjuster elements may not work with trackpad taps.

For each trial you define in an experiment script, you can make one or more 


 objects using 


Object and input them to addTrial.

For each trial you define in an experiment script, you can make one or more 


 objects using 


Object and input them to addTrial.

Input properties

Adjustable properties

You can allow the subject to adjust the following input properties of an object of this type during the experiment using an adjuster element. If you need to make other properties adjustable, you can copy the element type using newPbType and edit it.





No defaults

Properties = <cd>true<cd>/<cd>false<cd> setting adjustment mode. Set ONE of these = <cd>true<cd>:

drag_x = <cd>true<cd>: Subject adjusts by dragging the mouse cursor horizontally. Adjustment value is a number per distance dragged—see deltaRate below.

drag_y = <cd>true<cd>: Same but vertically.

drag_xy = <cd>true<cd>: Subject adjusts by dragging the mouse cursor in both dimensions. Adjustment value is a 1×2 vector per distance dragged (so typically the target you set in must be a 1×2 vector).


No default (ignored if move = <cd>true<cd> below)

A number that is adjustment value per distance dragged on screen. Magnitude is deltaRate × distance dragged. right/up = +, left/down = −. By default distance on screen is in deg, as usual. e.g.

drag_x = <cd>true<cd>
drag_y = <cd>false<cd> (default)
deltaRate = 0.5
→ +0.5/deg dragged right, −0.5/deg dragged left

If drag_xy = <cd>true<cd> then deltaRate can be a 1×2 vector setting separate rates for [x y].

Use adjust to set where and how adjustments are applied.


Default: apply adjustments of any magnitude

By default drag applies adjustments of any magnitude down to whatever corresponds to 1 px dragged on screen. However, some element properties can only receive adjustments that are multiples of some increment. e.g. a property that must be an integer can only receive adjustments that are integer multiples of 1. If so, you can set increment here (a number > 0). The adjuster will then buffer (not round or clip) adjustments to apply them in integer multiples of the increment. If drag_xy = <cd>true<cd> then deltaIncrement can be a 1×2 vector corresponding to separate increments for [x y]. 0 = apply adjustments of any magnitude.


Default: click anywhere to drag

Size of the area on screen that the subject can click in to start a drag. This is a number that is side length for a square, or a vector [width height] for a rectangle (deg). Or the number <cd>inf<cd> = click anywhere. Click area is centered at element position, which you can set in property position (default screen center).


Default: <cd>false<cd>

<cd>true<cd>/<cd>false<cd>: special mode to adjust target element position on screen by clicking & dragging the element. If = <cd>true<cd>:

  • must point to property position (e.g. <cds>"<element>.position"<cds>, or <cds>"<element>.position{1}"<cds> if you use a distance unit other than deg).
  • drag_x/drag_y/drag_xy above apply as usual: drag_x and drag_y send adjustments that are numbers, so typically set target to the corresponding position dimension (e.g. drag_y = <cd>true<cd> → target = <cds>"<element>.position(2)"<cds>). drag_xy sends adjustments that are 1×2 vectors, so typically set target to the whole position to move in both dimensions.
  • deltaRate, deltaIncrement, clickAreaSize above are ignored.


Default: button 1 drags, button 2 inputs response (done adjusting)

A number or vector that is mouse button number(s) to click to drag. All other buttons the subject can click to input that they are done adjusting (the "response").


Default: hand

A string or number setting mouse cursor shape. This goes to the type input of Psychtoolbox ShowCursor—see there for more information. Standard options are:


Input properties all visual elements have


Input properties all adjuster elements have


Input properties all objects have


Record properties

PsychBench uses record properties to record information during experiments. You can't set record properties but you can see them in experiment results using input property report.