data <- matrix(scan(),ncol=3,byrow=TRUE)
 1 1 26.1  1 2 22.7  1 3 22.5  1 4 22.6 
 2 1 81.0  2 2 53.2  2 3 53.7  2 4 53.1 
 3 1 10.5  3 2 9.7   3 3 10.8  3 4 8.3 
 4 1 26.6  4 2 19.6  4 3 21.1  4 4 21.6 
 5 1 12.9  5 2 13.8  5 3 13.7  5 4 13.3 
 6 1 57.2  6 2 47.1  6 3 39.2  6 4 37.0 
 7 1 25.0  7 2 13.6  7 3 13.7  7 4 14.8 
 8 1 20.3  8 2 23.6  8 3 16.3  8 4 14.8 

data

Potential1 <- data.frame(data)
colnames(Potential1) <- c("subject","emotion","SkinPotential")

levels(Potential1$emotion) <- c("Fear","Happiness","Depression","Calmness")

Potential1$subject  <- as.factor(Potential1$subject)      # to make sure that subject is a factor, not numeric 
Potential1$emotion  <- as.factor(Potential1$emotion)      # to make sure that emotion is a factor, not numeric

rm(data)
Potential1

summary(lm(SkinPotential ~ subject + emotion, data = Potential1))
anova(lm(SkinPotential ~ subject + emotion, data = Potential1))

par(mfrow=c(2,2))  
plot(lm(SkinPotential ~ subject + emotion, data = Potential1))          
par(mfrow=c(1,1)) 



friedman.test(SkinPotential ~ emotion | subject, data = Potential1)   
            # Friedman rank test, syntax is y ~ treatment | blocks