Unformatted text preview: and McClelland, 2001;
od, Howposterior probabilities. In this case, for a given weight
er. 1979).
Vickers, 1979).
df the co“natural
of evidence (e.g., is analogous to in Banburismus):
This problem the stopping point onedimensional
ponses and Turing’s Weight of Evidence
ted quanlar responses from a pair of sensory neurons when h a pairtrue, barriers (Link, 1992; Ratcliff
Brownian motion to or h is of as indicated. For
of tradePr(h1mmotion. The lower curve would
)
obabilities
es of a directionselective neuron that prefers upward The weight of evidence
articular
and Rouder, 1998).
means of the normal B
distribu(3)
log
ron” that prefers downward motion. Here wePr(h the simplifying assumption that the
make m)
surprisal”
r can be equal variances ( represent the drift rates, i (where the subscript i
tions ). Note that other0 forms of the distribution, including
f
and
and
bans but
old and Shadlen, 2001). The panelthe particular Turing’s weight of evidenceThe psychometon the
f reward
reflects B is a right shows motion strength).the barrier height
where
constant that represents
of their difference; note the linear relationship.
m of base
ric function describing the probability of correctly reachexclusive hypotheses
in favor of h1. For two mutually accumulate/integrate over
Decision Model
tiontime Figure 2. ing eitherh the is“up” r(h difference between equivalently, given) antineuron is:
or “down” barrier on a Pr(h trial
The weight (Pr(h favor of
evidence in m) over h
the accumulated m) or, responses of a neuron that prefers h and an
1depicted P computed under thetcondition) thatyh( is)true. The thin, wavy line depicts a simulated
1
0
0
ntlities has that prefers weight of7).evidence atare
motion
(
d (7)
total h (see Equation The curves
time1t k
ihich the trajectory that represents how the weight of evidence might grow on a single trial as a function of time. The dashed line depicts the expectation
0
Pr(h1)), and assuming the weight of evidence is exn motion
(mean value) of this trajectory at each time point. Note that changing the constant of proportionality used to rel...
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 Banburismus

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