# PARAMETERS AND OPTIONS # Each of the following lines consists of the name of a parameter/option, an equal sign, and a number - all separated by a space. # Please do not change the name of the parameter/option. # The denotations, that are included in brackets within the comment sections, refer to those used in Harris & Livesey (2010). # --------------------------------------------------------- # BASIC STRUCTURE OF THE NETWORK AND THE SIMULATION # Number of time steps in each trial. Please make sure that you specify enough time steps to present all stimuli and record # all activation as defined in the trial definition. Also bear in mind that stimuli decay gradually, i.e. a stimulus' units # may still be active after its offset. # We advise allowing at least 25 ticks beyond the offset of the last stimulus. num_TicksPerTrial = 50 # Number of elements representing each stimulus. Each stimulus specified in the stimulus definition is represented by several # elements that in turn consists of one E, I and A unit each. The activation of each of these units and their associations with each # other have to be updated in each time step using several iterations. Increasing the number of elements increases computing time # substantially. num_elements = 10 # Connectivity between E units. This parameter specifies the likelihood that one E unit is connected to another E unit. The # likelihoods of the two unidirectional connections between two E units are independent. Increasing the likelihood increases # the number of connections between E units and thus the learning speed. A likelihood of .5 maximises the variability across the # network that is necessary to solve certain learning tasks.If p is <1, the output of any single simulation will vary, and it is # therefore advisable to average across repeated simulations. For many simulated experiments, the connectivity does not have important # consequences for the simulation, and thus we advise setting p = 1 to avoid variability between simulations. connect_p = 1 # --------------------------------------------------------- # PARAMETERS FOR ACTVATION FUNCTION # Rule to calculate external sensory input (Sx) by a stimulus to its elements. Each stimulus activates a set of elements (or more # precisely, its E and A units). Their activation is determined by the minimal and maximal activation of this stimulus as specified # in the stimulus definition and the rule selected here. The simulator allows the user to choose between three different rules to # determine this external sensory input for each element: # 1 = linearly: input strengths are graded across elements of each stimulus in equal steps from the maximal to the minimal activation # 2 = randomly: for each element a value is drawn from the uniform distribution on the activation interval [minimum, maximum] # 3 = constant: all elements are activated to the mean of the minimal and maximal activation # If option 2 is selected, the output of any single simulation will vary, and it is therefore advisable to average across repeated # simulations. For many simulated experiments, the there is little difference between options 1 and 2 for the simulation. In such cases, # we advise selecting option 1 to avoid variability between simulations. S_distribution = 1 # Parameter for response potential functions of E, I and A units (Rpot): # Exponent (p) of response potential function (Rpot). Higher values of p make the response potential functions sigmoid and increase the # maximal slope. Power_E = 2 Power_I = 2 Power_A = 5 # Constant (D) of response potential function (Rpot). This parameter affects the relative sensitivity of the response potential to # an input and prevents the denominator ever being zero D = 0.04 # Rate parameters (delta) for change of the activation function (dR/dt). These two parameters control how fast the activation of # E, I, and A units actually rises and decays, respectively. # Rate parameters (delta) for rising of the activation (R), i.e. when the unit's response potential to its current input is higher # than its current activation ((Rpot -R)>0) Growth_E = 0.5 Growth_I = 0.5 Growth_A = 0.5 # Rate parameters (delta) for decay of the activation (R), i.e. when the unit's response potential to its current input is lower than # its current activation ((Rpot -R)<0) Decay_E = 0.2 Decay_I = 0.2 Decay_A = 0.2 # --------------------------------------------------------- # FIXED CONNECTION WEIGHTS AND NORMALIZATION # Normalisation based on similarity: Connection weight from E to I units of different elements (z). E units activate other elements' # I units and thus increase the inhibition of E units by I units, i.e. normalisation in the network. Instead of a graded change in # values of z across elements, three different degrees of normalisation can be specified: # (1) Normalisation of I units by E units of elements belonging to other stimuli. norm_across_all = 0.01 # (2) Normalisation of I units by E units of elements of other stimuli that share the same modality. The modality is specified in # the stimulus definition file. Stimuli with a modality of 0 do not share modality with any other stimulus. The follwoing value # will be divided number of elements in each stimulus. norm_within_modality = 0.5 # (3) Normalisation of I units by E units of other elements of the same stimulus. This value will be divided by the number of elements # in the stimulus. norm_within_stim = 0.5 # Normalisation based on A units # Connection weight from A to I unit (ka). A units inhibit I units of the same elements. Increasing the connection weight therefore # decreases normalisation of the E units. The parameter value should be positive (even though the connection is inhibitory). Weight_IA = 4 # Connection weight between A units (w): A units are in turn inhibited by other elements' A units. Increasing this connection weight # therefore increases normalisation of E units. The parameter value should be positive (even though the connection is inhibitory). Weight_AA = 0.1 # --------------------------------------------------------- # LEARNING PARAMETER # Parameter for coactivation function of two elements (DELTA). Changes in the connection weights between E units (i.e. the associative # strength V) depend on the coactivation of the two elements. The coactivation changes in response to increments in the recipient's E # and I units and is scaled by two rate parameters, betaE and betaI. As default, both parameters are set to 0 when the activation of E and I # is decaying, so that associative changes are driven only by increases in elements' activation. Increasing the parameter for rising # activation accelerates learning. # Parameter (betaE) for the effects of rising of recipient’s E unit's activation (dE_dt>0) Beta_E_pos = 0.02 # Parameter (betaE) for the effects of decay of recipient's E unit's activation (dE_dt<0) Beta_E_neg = 0.0 # Parameter (betaI) for the effects of rising of recipient’s I unit's activation (dI_dt>0) Beta_I_pos = 0.1 # Parameter (betaI) for the effects of decay of recipient’s I unit's activation (dI_dt<0) Beta_I_neg = 0.0 # Rate parameter (kV) for changes in connections weights function (dV_dt). This parameter controls how fast associative weights # are actually changing. The parameter value should be between 0 and 1. High values accelerates learning; low values results # in more stable learning. k_V = 1 # Rate parameter (kalpha) for changes in associability of sender's E unit function (dalpha_dt). This parameter controls how fast # associability is actually changing. The parameter should have values between 0 and 1. k_Alpha = 1 # --------------------------------------------------------- # OUTPUT OPTIONS # Figures: # Which figures should be created? 0 = no; 1= yes: # Final associative weights (i.e. connections between E units) at the end of the experiment fig_V = 1 # Activation of all E units in each time step fig_E = 0 # Activation of all I units in each time step fig_I = 0 # Activation of all A units in each time step fig_A = 0 # E units' activation, recorded and averaged for each trial as specified in the trial definition fig_CR = 1 # Output: how should the E units' activation, recorded and averaged for each trial as specified in the trial definition, be saved? # 0= not at all, # 1= as xls: each phase is saved in a separate sheet with the corresponding name # 2= as Matlab mat-file: each phase is saved in a cell of a cell array mat_CR = 1 #------------------------------------------------ # lines beginning with a hash are ignored # This file is part of a simulation programm for the Attention-Modulated Assocative Network (AMAN) # that can be downloaded from http://sydney.edu.au/science/psychology/staff/justinh/downloads/ # (see also Thorwart, Livesey & Harris, 2010)