Fix/Reward

Fixation Accuracy H, V : These define a rectangular window, in visual degrees subtended at the eye, around the current fixation target’s position. If the target position is (Tx, Ty) and the fixation accuracy is (Fx, Fy), then the fixation window is given by (Tx ± Fx, Ty ± Fy). As long as the eye position is within this window, the subject is considered to be fixating on target. The larger the window, the “looser” the constraints on fixation. Typically, larger windows are used during training. Again, these settings apply only to Continuous mode. The edit controls restrict input to floating-point numbers in [0.1 .. 50] degrees, with up to 2 digits after the decimal point.

Reward Pulse 1, 2 : These specify the desired length of reward pulses 1 & 2, in milliseconds. Any integer in [10 .. 500] is admissible. In Continuous mode, only reward pulse 1 applies. However, in trials featuring a two-choice protocol such as selByFix or switchFix, reward pulse 2 comes in to play. Note the checkbox labelled Override trial defn?; when checked, Maestro will use the reward pulse lengths specified here in lieu of the pulse lengths specified in each trial’s definition.

Reward Multiplier: (Added in Maestro v4.1.3; not shown in screenshot) All reward pulses delivered by Maestro are scaled by this value, then rounded to the nearest integer. At startup, this parameter always defaults to 1.0, which is the typical value for most experiments. Allowed range = [1..5]. Unlike the other settings on this panel, its value is not stored in the experiment document. Use case: To easily scale up delivered rewards if an animal is starting to lose interest toward the end of a long experimental session.

Random Withholding VR : VR stands for “variable ratio”, a term used in the literature on behavioral reinforcements. The feature is primarily intended for use during behavioral training. The edit control restricts input to an integer N in [1..10], in which case 1 in N earned rewards are randomly withheld from the subject on average. If N = 1 (the default), the feature is disabled and all earned rewards are given. The setting applies in both Continuous and Trial modes. Rarely used. NOTE: As of Maestro v4.1.0, WHVR can be specified on a per-trial basis, for each of the two reward pulses defined in a trial. This "global" WHVR should not be enabled when per-trial WHVR is in use.

Audio Reward : This edit control specifies the duration, in milliseconds, of an audible cue that is presented to the subject upon "earning" a reward, even if that reward is randomly withheld. Input is limited to integers in [100 .. 1000] or 0, which disables the cue. The cue is a simple tone played on an external speaker, assuming the rig is appropriately configured (the Digital I/O interface must include the "miscellaneous signals" plug-in module which, in turn, drives the speaker). The setting applies in both Trial and Continuous modes and is intended to be used in conjunction with random withholding. Rarely used.

Reward statistics: In the top-right hand corner of the dialog panel are two read-only numeric controls that display the total number of rewards delivered to the animal, and the cumulative length of the reward pulses in milliseconds. Some users refer to these statistics to get a rough idea of how much longer an animal will continue working effectively. They can be reset to zero at any time by clicking on the adjacent Reward Stats pushbutton.

Play reward indicator beep? checkbox : If this box is checked, then Maestro will play a brief tone a brief tone to let the investigator know that a reward was delivered in Trial or Continuous mode (do not confuse this audible indicator with the Audio Reward). In Maestro 3.x and earlier, the RTX driver would play a 1KHz tone lasting 200ms on the motherboard system speaker (IO port 0x61); of course, you would hear nothing if the system lacked the onboard speaker. Starting with Maestro 4, the beep is implemented by playing the "default system sound" using standard Windows audio. You will need to connect a speaker or headphones to the workstation's audio output in order to hear the sound. Also, be sure to use the Windows Control Panel to set the default system sound to a very short .WAV file (0.3sec or less); otherwise, the reward "beeps" could overlap when running trials that are only 1-2 seconds long! [Historical note: Why did earlier versions of Maestro not use Windows audio? In Maestro 2.x and earlier, we had to disable any non-essential devices, including sound cards, in order to have an available IRQ to assign to Maestro's DAQ board. This became a non-issue in Maestro 3.x, but we still used the system speaker because it worked. During testing of Maestro 4, we found that on some systems playing the beep on the system speaker caused unacceptable DAQ ISR latencies, due to system bus hijacking probably by the "PCI standard ISA bridge" device that that connects legacy devices like the motherboard speaker to the now-standard PCI Express bus. Hence, we decided to implement the beep with Windows audio, as it is no longer necessary to disable the audio device in order for Maestro to run.]