STATS 787
Visual Perception

Reminders

  • Lab 10 (due week 12)

Visual Channels

  • Mapping data values to aesthetic values (ggplot2) is encoding data values as visual channels (visual perception).

ggplot(mtcars) +
    geom_bar(aes(am))

ggplot(mtcars) +
    geom_bar(aes(factor(am), fill=factor(am)))

Visual Channels

  • Some visual channels are more effective than others (for numeric data).

ggplot(mtcars) +
    geom_bar(aes(factor(am), fill=factor(am)))

ggplot(mtcars) +
    geom_bar(aes(x="", fill=factor(am))) + 
    coord_polar(theta="y")

Preattentive Pop Out

  • Some visual channels form groups very easily.
  • Some channels are stronger than others.
  • Too many channels at once ruins it.

Gestalt Rules

  • There are other visual features that form groups easily.

Colour

  • Hues are good for groups.
  • Chroma and luminance are ok for numeric data.

Colour-Vision Deficiency

fills <- scales::pal_hue()(2)
ggplot(mtcars) +
    geom_bar(aes(factor(am), fill=factor(am)))

fills <- scales::pal_hue()(2)
ggplot(mtcars) +
    geom_bar(aes(factor(am), fill=factor(am))) +
    scale_fill_manual(values=colorspace::deutan(fills))

Visual Illusions

Visual Illusions