# Discrimination Accuracy of Sequential Versus Simultaneous Vibrotactile Stimulation on the Forearm
## 4 Results  
A repeated measures ANOVA was conducted to examine the effects of the presentation mode (simultaneous or sequential) and the length of the patterns (short or long) on the accuracy of vibrotactile pattern reproduction. The results showed that both the presentation mode (F (1, 20) = 1033; \(p\) = 1.07 \(\times\) 10\({}^{-18}\)) and the length of patterns (F (1, 20) = 53.6; \(p\) = 4.41 \(\times\) 10\({}^{-7}\)) had a significant effect on accuracy. Accuracy was significantly higher with sequential presentation than simultaneous, and performance was better for short vibrotactile patterns than long ones. Additionally, there was a significant interaction between these two factors (F (1, 20) = 12.4; \(p\) = 0.02; \(p\) < 0.05), indicating that the effect of pattern length on accuracy differed depending on the presentation method.  
We defined 'accuracy' as the participant's ability to correctly recognize and report the vibrotactile patterns applied to the skin of their forearm. For sequential activation, a 'correct response' meant that participants accurately identified and reported all the activations in the presented sequence and, importantly, maintained their correct order. The order in which they reported the dots was therefore critical for accuracy. In contrast, for simultaneous presentation, a 'correct response' was determined by participants' accurate identification of the numbered actuators in the pattern. The order in which participants reported the vibrations therefore did not affect accuracy.  
Figure 3: (**a**) A participant in the anechoic chamber wearing a vibrotactile sleeve, with his hand resting on a cushion. The participants wore headphones playing white noise to block out external auditory cues and responded to the vibrotactile feedback by pressing the correct keys on the keypad. (**b**) The audio hardware consisted of a digital audio interface (RME MADI face XT), digital-to-analog converters (Ferrofish A32), multi-channel amplifiers, and parallel vibrating voice coil actuators (Lofelt L5), t L5). The MADI face XT receives information from a computer via a USB cable and sends the signal to the Ferrofish A32 Analog-to-Digital/Digital-to-Analog (AD/DA) converter. Ferrofish A32 then conveys the signal to the amplifier, which then sends the amplified signal to the actuators.  
The data in Figure 4 reveal that the detrimental effect of simultaneous presentation was larger for the long patterns than the short ones. Overall, these findings suggest that the presentation method has a large effect on the accuracy of vibrotactile pattern recognition. In addition, there was a large effect of the pattern length (short versus long).  
The box plots (Figure 4) show how the median accuracy was highest for sequential presentation for both short (97.19%) and long patterns (89.29%). The most notable result is that presenting vibrotactile patterns sequentially was vastly more effective for accuracy for both short and long patterns. Another important result is that accuracy during simultaneous presentation was much lower for long patterns (15.28%) than short ones (37.80%).