Psychophysics on LabBench, Version 6.0

Cold Pressor

Mon, 01 Jan 0001 00:00:00 +0000

The cold pressor procedure measures pain detection (PDT) and/or pain tolerance (PTT) based on timed button presses during hand immersion in cold water. The procedure is event-driven and records the time between key events: immersion, pain onset, and withdrawal.

During execution, instructions are presented to guide the operator or participant through the task. Button presses mark transitions between phases, and timing is recorded automatically.

After completion, the result is visualized as a timeline, showing the measured thresholds and overall duration of the procedure.

Manual Threshold Estimation

Mon, 01 Jan 0001 00:00:00 +0000

The manual threshold estimation procedure is used when LabBench cannot control the stimulus directly, and the experimenter must apply it manually. It consists of a response task and an estimation algorithm: the participant performs a perception task in which responses are classified as correct or incorrect, and an adaptive algorithm uses these outcomes to update estimates of the threshold or psychometric function. The stimulus is implicitly defined by the response task, and estimation is performed over an independent variable (x), where increasing x is assumed to increase the probability of a correct response.

Response Recording

Mon, 01 Jan 0001 00:00:00 +0000

The response recording test implements computerized psychophysical ratings that allow a subject to rate a sensation sampled continuously for either a fixed time or a time determined by events during the test. Computerized psychophysical ratings allow time-dependent quantification of psychophysiological responses, such as the area under the curve, the maximal rating, or the time of maximal rating. Optionally, the test can be amended to include simultaneous recording of signals, either stimuli (e.g., stimulation pressure) or biophysical signals (e.g., heart rate or galvanic skin response). It is also possible to define events that can occur during the test; this will allow the experimenter to mark the times these events occur in the test’s recorded data.

Stimulus Presentation

Mon, 01 Jan 0001 00:00:00 +0000

The Stimulus Presentation procedure allows a participant to become familiar with a stimulus and to rate its sensation on a psychophysical rating scale.

The procedure can also be used to manually find thresholds, as the last tested intensity is available in the calculated parameter [ProcedureID].Intensity upon completion.

The procedure window for the procedure is shown in Figure 1. It consists of three main areas: responses, stimulus display, and stimulation and intensity control.

Threshold Estimation

Mon, 01 Jan 0001 00:00:00 +0000

The threshold estimation test uses adaptive methods to efficiently estimate a participant’s perceptual threshold or full psychometric function. Instead of presenting a fixed set of stimulus intensities, adaptive methods adjust stimulus levels in real time based on the participant’s responses. Adaptive methods allow the experimenter to concentrate trials around the most informative stimulus range—typically near the participant’s threshold—thereby reducing the total number of trials needed compared to non-adaptive (e.g., method of constant stimuli) approaches.