Accessing variables in closure in R

In the following example, why do f$i and f$get_i() return different results?

factory <- function() {

  my_list <- list()
  my_list$i <- 1

  my_list$increment <- function() {
    my_list$i <<- my_list$i + 1
  }

  my_list$get_i <- function() {
    my_list$i
  }

  my_list
}

f <- factory()

f$increment()
f$get_i() # returns 2
f$i # returns 1