Description Usage Arguments Details Value Note Author(s) References

DIVergent Autoencoder (Kurtz, 2007; 2015) artificial neural network category learning model

1 |

`st` |
List of model parameters |

`tr` |
R-by-C matrix of training items |

`xtdo` |
When set to TRUE, produce extended output |

This function works as a stateful list processor (Wills et al., 2017). Specifically, it takes a matrix as an argument, where each row is one trial for the network, and the columns specify the input representation, teaching signals, and other control signals. It returns a matrix where each row is a trial, and the columns are the response probabilities for each category. It also returns the final state of the network (connection weights and other parameters), hence its description as a 'stateful' list processor.

Argument `st`

must be a list containing the following items:

`st`

must contain the following principal model parameters:

`learning_rate`

- Learning rate for weight updates through
backpropagation. The suggested learning rate default is
`learning_rate = 0.15`

`beta_val`

- Scalar value for the Beta parameter. `beta_val`

controls the degree of feature focusing (not unlike attention) that
the model uses to make classification decisions (see: Conaway & Kurtz,
2014; Kurtz, 2015). `beta_val = 0`

turns feature focusing off.

`phi`

- Scalar value for the phi parameter. `phi`

is a
real-valued mapping constant, see Kruschke (1992, Eq. 3).

`st`

must also contain the following information about network
architecture:

`num_feats`

- Number of input features.

`num_hids`

- Number of hidden units. A rough rule of thumb for
this hyperparameter is to start with `num_feats = 2`

and add
additional units if the model fails to converge.

`num_cats`

- Number of categories.

`continuous`

- A Boolean value to indicate if the model should
work in continuous input or binary input mode. Set ```
continuous =
TRUE
```

when the inputs are continuous.

`st`

must also contain the following information about the
initial state of the network:

`in_wts`

- A matrix of initial input-to-hidden weights with
`num_feats + 1`

rows and `num_hids`

columns. Can be set to
`NULL`

when the first line of the `tr`

matrix includes
control code 1, `ctrl = 1`

.

`out_wts`

- A matrix of initial hidden-to-output weights with
`num_feats + 1`

rows, `num_hids`

columns and with the third
dimension being `num_cats`

in extent. Can be set to `NULL`

when the first line of the `tr`

matrix includes control code 1,
`ctrl = 1`

.

`st`

must also contain the following information so that it can
reset these weights to random values when ctrl = 1 (see below):

`wts_range`

- A scalar value for the range of the
randomly-generated weights. The suggested weight range deafult is
`wts_range = 1`

`wts_center`

- A scalar value for the center of the
randomly-generated weights. This is commonly set to ```
wts_center =
0
```

`st`

must also contain the following parameters that describe
your `tr`

array:

`colskip`

- Skip the first N columns of the tr array, where
`N = colskip`

. `colskip`

should be set to the number of
optional columns you have added to matrix `tr`

, PLUS ONE. So, if
you have added no optional columns, `colskip = 1`

. This is
because the first (non-optional) column contains the control values,
below.

Argument `tr`

must be a matrix, where each row is one trial
presented to the network. Trials are always presented in the order
specified. The columns must be as described below, in the order
described below:

`ctrl`

- column of control codes. Available codes are: 0 = normal
learning trial, 1 = reset network (i.e. initialize a new set of
weights following the `st`

parameters), 2 = Freeze
learning. Control codes are actioned before the trial is processed.

`opt1, opt2, ...`

- optional columns, which may have any names
you wish, and you may have as many as you like, but they must be
placed after the `ctrl`

column, and before the remaining columns
(see below). These optional columns are ignored by this function, but
you may wish to use them for readability. For example, you might
include columns for block number, trial number, and stimulus ID
number. The argument `colskip`

(see above) must be set to the
number of optional columns plus 1.

`x1, x2, ...`

- input to the model, there must be one column for
each input unit. Each row is one trial. Dichotomous inputs should be
in the format `-1, 1`

. Continuous inputs should be scaled to the
range of `-1, 1`

. As the model's learning objective is to
accurately reconstruct the inputs, the input to the model is also the
teaching signal. For testing under conditions of missing information,
input features can be set to 0 to negate the contribution of the
feature(s) for the classification decision of that trial.

`t1, t2, ...`

- Category membership of the current
stimulus. There must be one column for each category. Each row is one
trial. If the stimulus is a member of category X, then the value in
the category X column must be set to `+1`

, and the values for all
other category columns must be set to `-1`

.

Returns a list containing two components: (1) matrix of response
probabilities for each category on each trial, (2) an `st`

list
object that contains the model's final state. A weight initialization
history is also available when the extended output parameter is set
`xtdo = TRUE`

in the `slpDIVA`

call.

A faster (Rcpp) implementation of slpDIVA is planned for a future release of catlearn.

Garrett Honke, Nolan B. Conaway, Andy Wills

Conaway, N. B., & Kurtz, K. J. (2014). Now you know it, now you don't:
Asking the right question about category knowledge. In P. Bello,
M. Guarini, M. McShane, & B. Scassellati (Eds.), *Proceedings of
the Thirty-Sixth Annual Conference of the Cognitive Science Society*
(pp. 2062-2067). Austin, TX: Cognitive Science Society.

Kruschke, J. (1992). ALCOVE: an exemplar-based connectionist model of
category learning. *Psychological Review, 99*, 22-44

Kurtz, K.J. (2007). The divergent autoencoder (DIVA) model of category
learning. *Psychonomic Bulletin & Review, 14*, 560-576.

Kurtz, K. J. (2015). Human Category Learning: Toward a Broader
Explanatory Account. *Psychology of Learning and Motivation, 63*.

Wills, A.J., O'Connell, G., Edmunds, C.E.R., & Inkster,
A.B.(2017). Progress in modeling through distributed collaboration:
Concepts, tools, and category-learning examples. *The Psychology
of Learning and Motivation, 66*, 79-115.

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