User Reference:CursorTask

Function

The CursorTask displays a box-shaped scene in which a ball-shaped cursor moves in 2 or 3 dimensions, controlled by the output of the Signal Processing Module. In this scene, targets appear as cuboids or rectangles. Box, cursor, and targets may be texturized.

Time Line

Parameters

Sequencing

PreRunDuration

The duration of the pause preceding the first trial. Given in sample blocks, or in time units when immediately followed with 's', 'ms', or similar.

PreFeedbackDuration

The duration of target display before feedback begins. Given in sample blocks, or in time units when immediately followed with 's', 'ms', or similar.

FeedbackDuration

Typical duration of feedback. Given in sample blocks, or in time units when immediately followed with 's', 'ms', or similar.

This parameter is not a hard limit to feedback duration but determines cursor speed such that, for a normalized control signal, cursor movement will take the specified time from the cursor's starting point to the screen's edge. Feedback trials will typically have this duration, provided that the cursor starts at the center of the screen, targets are located at the screen's edges, and ignoring cursor and target width (for further details, see User Reference:Normalizer).

PostFeedbackDuration

The duration of result display after feedback. Given in sample blocks, or in time units when immediately followed with 's', 'ms', or similar.

ITIDuration

The duration of the inter-trial interval. Given in sample blocks, or in time units when immediately followed with 's', 'ms', or similar.

NumberOfTrials

The number of trials in a run. If this parameter is set, then MinRunLength should be blank, and vice-versa.

MinRunLength

The duration of a run, i.e. the time corresponding to a continuously recorded data file. A run will not stop during a trial, so its actual length may be larger than this value by the length of a trial. If this parameter is set, then NumberOfTrials should be blank, and vice-versa. Given in sample blocks, or in time units when immediately followed with 's', 'ms', or similar.

NumberTargets

The number of targets on the feedback screen.

TargetSequence

A list of indices, each one being from 1 to NumberTargets. This list specifies an optional fixed sequence of stimuli, through which the presentation will cycle. Leave this parameter blank if you want the default behavior, which is for stimuli to be selected randomly.

States

PreStimulusTime

A 16-bit time stamp in the same format as the SourceTime state. This time stamp is set immediately before the application module is going to update the stimulus/feedback display. Note that a data block is saved together with the state vector that existed immediately after it was acquired. Thus, PreStimulusTime will be the prestimulus time of the block prior to the current block.

StimulusTime

A 16-bit time stamp in the same format as the SourceTime state. This time stamp is set immediately after the application module has updated the stimulus/feedback display. Note that a data block is saved together with the state vector that existed immediately after it was acquired. Thus, StimulusTime will be the stimulus time of the block prior to the current block.

PresentationRequested

This 32-bit state contains a list of ids for all presentations that have been requested during the current block. The list ends with a value of 2^31. A 32-bit presentation id is formed by combining the 16-bit SourceTime state of the presentation request's data block in the most significant bits, with the time difference between that source time stamp and the time when the presentation request happened, in the least significant bits:

PresentationID = SourceTime << 8 | (RequestTime - SourceTime) & 0xff

This definition makes presentation ids unique within the range of a minute, and allows to extract the value of the request's time stamp from its id.

PresentationDisplayed

This 32-bit state contains a list of ids for all presentations that have been displayed during the current block. The list ends with a value of 2^31. Presentation ids appear in the PresentationRequested state when presentation is requested, and subsequently in the PresentationDisplayed state when presentation has occurred.

PresentationTime

A 16-bit time stamp in the same format as the SourceTime state. For each id occurring in the PresentationDisplayed state, this state contains the time stamp of the respective update to video memory. From this point in time, up to two additional frame durations may be required before the display's surface actually shows a difference in signal. This depends on the internals of the display, and cannot be determined from software.

PresentationFrame

A 12-bit state that contains, for each id occurring in the PresentationDisplayed state, the frame number of the respective update to video memory. Frame numbers have an arbitrary offset, and wrap around at a value of 2^11.

AudioBufferTime

A 16-bit time stamp in the same format as the SourceTime state. For each audio presentation that has occurred during the current block, this state contains the time stamp when non-zero audio data were about to enter the system's audio buffer.

AudioPresentationTime

A 16-bit time stamp in the same format as the SourceTime state. For each audio presentation that has occurred during the current block, this state contains the estimated time stamp when non-zero audio data were being played from the system's speakers or headphones. The estimate takes the length of the system's audio buffers into account but will not be able to detect external sources of delays, such as additional audio processing steps.

See also

Control Signal