Rational Speech Act pragmatic listener and speaker

A small, self-contained RSA recursion over a word-by-object meaning matrix (Frank & Goodman, 2012; Smith, Goodman & Frank, 2013), used by predict_referent() with pragmatic = TRUE. rsa_listener() returns P(object | word) for a listener who reasons about an informative speaker; rsa_speaker() returns P(word | object) for that speaker. Both operate on any non-negative (word x object) matrix, reading entries as literal meaning weights.

Usage

rsa_listener(lex, prior, ...)

rsa_speaker(lex, prior, ...)

Arguments

lex

A (word x object) matrix of literal meaning weights.

prior

Numeric prior over objects (one per column of lex). Objects with prior 0 are dropped from the reasoning and get listener probability 0.

...

Further arguments to the recursion: alpha (speaker rationality / softmax temperature, default 3), cost (optional per-word production cost vector), and depth (pragmatic recursions beyond the literal level; 0 gives the prior-weighted literal listener, 1 the usual one-step pragmatic one).

Value

rsa_listener(): a (word x object) matrix of P(object | word). rsa_speaker(): a (word x object) matrix of P(word | object).

Examples

# "wug" names either object; a pragmatic listener resolves it to the second
lex <- matrix(c(1, 0, 1, 1), 2, byrow = TRUE)
rsa_listener(lex, c(0.5, 0.5), alpha = 3, depth = 1)
#>      [,1] [,2]
#> [1,]  1.0  0.0
#> [2,]  0.1  0.9