En Excel, con datos organizados así:

                                              Bare NP                   Singular-Marked NP               Plural-Marked NP   
                                    BrP Speakers    AmE Speakers    BrP Speakers    AmE Speakers    BrP Speakers AmE Speakers
Plural Interpretation               0.005747126 0.006896552         0.194117647 0.124567474         0.872093023 0.985815603
Plural & Singular Interpretation    0.649425287 0.910344828         0.029411765 0.051903114         0.127906977 0.014184397
Singular Interpretation             0.344827586 0.082758621         0.776470588 0.823529412         0           0

Soy capaz de producir un gráfico de barras apiladas que se ve así:

¿Hay una manera fácil de reproducir la forma en que el eje x se divide en las condiciones separadas (es decir, "Bare NP", "Singular-Marked NP", y "Plural-Marked NP") usandoR?

Todo lo que puedo decir en este momento es esto:

pluralInterp <- c(0.005747126,0.006896552,0.194117647,0.124567474,0.872093023,0.985815603)

pluralAndSingInterp <- c(0.649425287,0.910344828,0.029411765,0.051903114,0.127906977,0.014184397)

singInterp <- c(0.344827586,0.082758621,0.776470588,0.823529412,0,0)

a  <- rbind(pluralInterp,pluralAndSingInterp,singInterp)

colnames(a) <- c("Bare NP ~ BrP Speakers",
                 "Bare NP ~ AmE Speakers",
                 "Singular-Marked NP ~ BrP Speakers",
                 "Singular-Marked NP ~ AmE Speakers",
                 "Plural-Marked NP ~ BrP Speakers",
                 "Plural-Marked NP ~ AmE Speakers"
                 )

barplot(a,
        col=c("blue","red","purple"),
        ylab="Frequency of Interpretation",
        xlab="Form of NP and Native Language",
        main="Frequency of BrP and AmE Interpretations of NPs in Neutral Environments"
        )

Que produce el siguiente gráfico: