The reported efficacy of biofeedback is not consistent across studies. One issue that has not been addressed in previous studies is the effect of the reference signal in a biofeedback system.

We compared the effects of two different reference signals using a computational model and human experiments. One reference signal was fixed, and the other was variable and was designed based on time-delayed feedback control concepts. The computational model consists of a plant and a controller. Groups of typically developing and children with attention deficit disorder (ADD) participated in our experiments.

The computational model showed that time-delayed reference feedback control could have more positive effects on the performance than using a fixed reference signal. The model prediction was consistent with the results obtained from the experiments performed on children with ADD. However, in typically developing children, using time-delayed reference feedback control had a negative effect. Our preliminary results, which need to be investigated on more subjects, indicate the importance of selecting the reference signal in biofeedback systems according to the characteristics of each participant. The results remind the importance of “single-case methodology” in neurocognitive rehabilitation systems. Using computational concepts, some other predictions have also been provided, which need more investigations.

报告的生物反馈功效在研究之间不一致。在以前的研究中尚未解决的一个问题是参考信号在生物反馈系统中的作用。

我们使用计算模型和人体实验比较了两种不同参考信号的影响。一个参考信号是固定的，而另一个则是可变的，并且是基于延时反馈控制概念设计的。计算模型由一个工厂和一个控制器组成。典型发育中的儿童和患有注意缺陷障碍（ADD）的儿童参加了我们的实验。

计算模型表明，与使用固定参考信号相比，延时参考反馈控制对性能的影响更大。模型预测与从对ADD儿童进行的实验获得的结果一致。但是，在通常发育的儿童中，使用延时的参考反馈控制会产生负面影响。我们需要对更多主题进行研究的初步结果表明，根据每个参与者的特征在生物反馈系统中选择参考信号的重要性。结果提醒了“单例方法”在神经认知康复系统中的重要性。使用计算概念，还提供了其他一些预测，需要进行更多研究。