• Figure 2.
    Download figureOpen in new tabFigure 2. Schematic diagram illustrating the process of perceptual decision making, and the possible influence of the motor cost on the decision process.

    Perceptual decision making consists of three different processing stages. First, the features of the sensory input are extracted and encoded as in the sensory representation. Second, the perceptual (categorical) decision is made based on this sensory representation (decision layer). Finally, the decision is transferred to the response effector. The motor cost asymmetry during the manual response can affect the perceptual decision making process in several different ways. (A) The motor cost for the manual response may only bias the decision layer that involves this response, but leave the decision layer for different response effectors unaffected. If this is the case, the bias observed during the manual response should not generalise to the verbal response. (B) The motor cost may bias the decision layer in general or (C) the sensory representation directly. In either of the latter two cases, the effect of motor cost should be also observable during the response using the different effector.

    DOI: http://dx.doi.org/10.7554/eLife.18422.006

  • Table 1.

    BIC and BIC weights calculated for different DDM. *BIC and the BIC weights for different DDM models. Values calculated using the group averaged data, and the 95% confidence interval is calculated from the 10,000 bootstrap resampling is presented.

    DOI: http://dx.doi.org/10.7554/eLife.18422.010



    Starting point modelSensory evidence modelFull modelBaseline model
    BIC
    (95% confidence
    interval)
    averaged346.09360.37348.76432.88
    upper bound433.94447.89441.07547.49
    lower bound335.04348.64337.62401.31
    BIC weight
    (95% confidence
    interval)
    averaged0.79110.00060.20830.0000
    upper bound0.8600
    0.4303
    0.7445
    0.0000
    lower bound0.0600
    0.0000
    0.1336
    0.0000
  • Table 2.

    Parameter estimates for data from Experiment 1-4 for the starting point and sensory evidence model. *Parameters for the simulations for the error RTs were chosen to be these fitted parameters.

    DOI: http://dx.doi.org/10.7554/eLife.18422.015

    DDM parameterskABT01(dTA)T02(dTB)spdcoh
    starting point model0.29
    11.76
    12.02
    460 (−9)459 (−28)−1.62
    0
    sensory evidence model0.29
    11.59
    12.20
    460 (−17)458 (−22)0
    4.00