diff --git a/Project.toml b/Project.toml
index 1d26760..e6f4fe6 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,7 +1,7 @@
 name = "ACTRModels"
 uuid = "c095b0ea-a6ca-5cbd-afed-dbab2e976880"
 authors = ["itsdfish"]
-version = "0.6.1"
+version = "0.6.2"
 
 [deps]
 DataFrames = "a93c6f00-e57d-5684-b7b6-d8193f3e46c0"
diff --git a/src/MemoryFunctions.jl b/src/MemoryFunctions.jl
index 38e09e1..9fcd52b 100644
--- a/src/MemoryFunctions.jl
+++ b/src/MemoryFunctions.jl
@@ -1,5 +1,7 @@
 """
-**baselevel** computes baselevel activation according exact equation
+**baselevel** 
+
+Computes baselevel activation according exact equation
 * `d`: decay parameter
 * `lags`: a vector of time lags between current time and each usage time
 
@@ -7,7 +9,7 @@ Function Signature
 ````julia 
 baselevel!(actr, chunk)
 ````
-Function Signature
+**Function Signature**
 ````julia
 baselevel(d, lags)
 ````
@@ -21,11 +23,13 @@ function baselevel(d, lags)
 end
 
 """
-**baselevel!** computes baselevel activation according to the hybrid approximation
+**baselevel!** 
+
+Computes baselevel activation according to the hybrid approximation
 * `actr`: ACTR object
 * `chunk`: a chunk
 
-Function Signature
+**Function Signature**
 ````julia 
 baselevel!(actr, chunk)
 ````
@@ -46,11 +50,13 @@ function baselevel!(actr, chunk)
 end
 
 """
-**baselevel!** computes baselevel activation for all chunks in declarative memory
+**baselevel!** 
+
+Computes baselevel activation for all chunks in declarative memory
  according to the hybrid approximation
 * `actr`: ACTR object
 
-Function Signature
+**Function Signature**
 ````julia 
 baselevel!(actr)
 ````
@@ -58,13 +64,15 @@ baselevel!(actr)
 baselevel!(actr) = activation!.(actr, memory.memory)
 
 """
-**compute_activation!* computes the activation of a set of chunks
+**compute_activation!* 
+
+Computes the activation of a set of chunks
 - `actr`: actr object
 - `chunks`: a set of chunks.
 - `cur_time`: current time. Default 0.0 used when bll is false
 - `request`: optional NamedTuple for retrieval request
 
-Function Signature
+**Function Signature**
 ````julia 
 compute_activation!(actr::AbstractACTR, chunks::Vector{<:Chunk}, cur_time::Float64=0.0; request...)
 ````
@@ -83,13 +91,15 @@ function compute_activation!(actr::AbstractACTR, chunks::Vector{<:Chunk}, cur_ti
 end
 
 """
-**compute_activation!* computes the activation of a chunk
+**compute_activation!**
+
+Computes the activation of a chunk
 - `actr`: actr object
 - `chunk`: a chunk
 - `cur_time`: current time. Default 0.0 used when bll is false
 - `request`: optional keyword arguments for retrieval request
 
-Function Signature
+**Function Signature**
 ````julia 
 compute_activation!(actr, chunk::Chunk, cur_time=0.0; request...)
 ````
@@ -97,12 +107,14 @@ compute_activation!(actr, chunk::Chunk, cur_time=0.0; request...)
 compute_activation!(actr, chunk::Chunk, cur_time=0.0; request...) = compute_activation!(actr, [chunk], cur_time; request...)
 
 """
-**compute_activation!* computes the activation for all declarative memory
+**compute_activation!** 
+
+Computes the activation for all declarative memory
 - `actr`: actr object
 - `cur_time`: current time. Default 0.0 used when bll is false
 - `request`: optional keyword arguments for retrieval request
 
-Function Signature
+**Function Signature**
 ````julia 
 compute_activation!(actr::AbstractACTR, cur_time::Float64=0.0; request...)
 ````
@@ -110,13 +122,15 @@ compute_activation!(actr::AbstractACTR, cur_time::Float64=0.0; request...)
 compute_activation!(actr::AbstractACTR, cur_time::Float64=0.0; request...) = compute_activation!(actr, actr.declarative.memory, cur_time; request...)
 
 """
-**activation!** computes activation for a given chunk
+**activation!** 
+
+Computes activation for a given chunk
 - `actr`: ACT-R object
 - `chunk`: chunk object
 - `cur_time`: current time, default = 0
 - `request`: optional keyword arguments for retrieval request
 
-Function Signature
+**Function Signature**
 ````julia
 activation!(actr, chunk::Chunk, cur_time=0.0; request...)
 ````
@@ -155,10 +169,12 @@ function reset_activation!(chunk)
 end
 
 """
-**total_activation!** sums activation across all components
+**total_activation!** 
+
+Sums activation across all components
 - `chunk`: chunk object
 
-Function Signature
+**Function Signature**
 ````julia
 total_activation!(chunk)
 ````
@@ -178,12 +194,14 @@ function add_noise!(actr, chunk)
 end
 
 """
-**partial_matching!** computes activation for partial matching component
+**partial_matching!** 
+
+Computes activation for partial matching component
 - `actr`: an ACTR object
 - `chunk`: a chunk 
 - `request...`: optional keyword arguments for retrieval request
 
-Function Signature
+**Function Signature**
 ````julia
 partial_matching!(actr, chunk; request...)
 ````
@@ -195,11 +213,13 @@ function partial_matching!(actr, chunk; request...)
 end
 
 """
-**set_noise!** sets noise true or false.
+**set_noise!** 
+
+Sets noise true or false.
 * `actr`: ACTR object
 * `b`: boolean value
 
-Function Signature
+**Function Signature**
 ````julia
 set_noise!(actr::AbstractACTR, b)
 ````
@@ -209,11 +229,13 @@ function set_noise!(actr, b)
 end
 
 """
-**spreading_activation** computes the spreading activation for a given chunk
+**spreading_activation** 
+
+Computes the spreading activation for a given chunk
 * `actr`: actr object or declarative memory object
 * `chunk`: the chunk for which spreading activation is computed
 
-Function Signature
+**Function Signature**
 ````julia
 spreading_activation!(actr, chunk)
 ````
@@ -265,12 +287,14 @@ function count_values(chunk, value)
 end
 
 """
-**update_recent** adds a new timestamp to chunk and removes oldest timestamp if
+**update_recent** 
+
+Adds a new timestamp to chunk and removes oldest timestamp if
 length equals k.
 * `chunk`: memory chunk object
 * `cur_time`: current time in seconds
 
-Function Signature
+**Function Signature**
 ````julia
 update_recent!(chunk, cur_time)
 ````
@@ -285,13 +309,15 @@ function update_recent!(chunk, cur_time)
 end
 
 """
-**retrieval_prob** computes the retrieval probability of one chunk from a set of chunks defined in `target`.
+**retrieval_prob** 
+
+Computes the retrieval probability of one chunk from a set of chunks defined in `target`.
 * `actr`: an actr object
 * `chunk`: a chunk
 * `cur_time`: current time. Default 0.0 to be used when bll is false
 * `request`: optional NamedTuple for retrieval request
 
-Function Signature
+**Function Signature**
 ````julia
 retrieval_prob(actr::AbstractACTR, target::Array{<:Chunk,1}, cur_time=0.0; request...)
 ````
@@ -315,13 +341,15 @@ function retrieval_prob(actr::AbstractACTR, target::Array{<:Chunk,1}, cur_time=0
 end
 
 """
-**retrieval_prob** computes the retrieval probability of retrieving a chunk.
+**retrieval_prob** 
+
+Computes the retrieval probability of retrieving a chunk.
 * `actr`: an actr object
 * `chunk`: a chunk
 * `cur_time`: current time. Default 0.0 to be used when bll is false
 * `request`: optional NamedTuple for retrieval request
 
-Function Signature
+**Function Signature**
 ````julia
 retrieval_prob(actr::AbstractACTR, chunk::Chunk, cur_time=0.0; request...)
 ````
@@ -343,12 +371,14 @@ function retrieval_prob(actr::AbstractACTR, chunk::Chunk, cur_time=0.0; request.
 end
 
 """
-**retrieval_probs** computes the retrieval probability for each chunk matching the retrieval request.
+**retrieval_probs** 
+
+Computes the retrieval probability for each chunk matching the retrieval request.
 * `actr`: an actr object
 * `cur_time`: current time. Default 0.0 to be used when bll is false
 * `request`: optional NamedTuple for retrieval request
 
-Function Signature
+**Function Signature**
 ````julia
 retrieval_probs(actr::AbstractACTR, cur_time=0.0; request...)
 ````
@@ -369,11 +399,13 @@ function retrieval_probs(actr::AbstractACTR, cur_time=0.0; request...)
 end
 
 """
-**update_lags** compute lags for each use of a chunk.
+**update_lags** 
+
+Compute lags for each use of a chunk.
 * `chunk`: a chunk
 * `cur_time`: current time. Default 0.0 to be used when bll is false
 
-Function Signature
+**Function Signature**
 ````julia
 update_lags!(chunk::Chunk, cur_time)
 ````
@@ -385,11 +417,13 @@ function update_lags!(chunk::Chunk, cur_time)
 end
 
 """
-**update_lags** compute lags for each use of a chunk. Applies to all chunks in declarative memory.
+**update_lags** 
+
+Compute lags for each use of a chunk. Applies to all chunks in declarative memory.
 * `actr`: an ACTR object
 * `cur_time`: current time. Default 0.0 to be used when bll is false
 
-Function Signature
+**Function Signature**
 ````julia
 update_lags!(actr::AbstractACTR, cur_time)
 ````
@@ -397,7 +431,9 @@ update_lags!(actr::AbstractACTR, cur_time)
 update_lags!(actr::AbstractACTR, cur_time) = update_lags!(actr.declarative, cur_time)
 
 """
-**update_lags** compute lags for each use of a chunk. Applies to all chunks in declarative memory.
+**update_lags** 
+
+Compute lags for each use of a chunk. Applies to all chunks in declarative memory.
 * `memory`: a declarative memory object object
 * `cur_time`: current time. Default 0.0 to be used when bll is false
 
@@ -415,13 +451,15 @@ function update_chunk!(chunk, cur_time)
 end
 
 """
-**add_chunk!** new chunk to declarative memory or updates existing chunk with new use
+**add_chunk!** 
+
+Adds new chunk to declarative memory or updates existing chunk with new use
 * `memory`: declarative memory object
 * `cur_time`: current time, default = 0.0
 * `act`: optional activation value
 * `slots`: optional keyword arguments corresponding to slot-value pairs, e.g. name=:Bob
 
-Function Signature
+**Function Signature**
 ````julia
 add_chunk!(memory::Declarative, cur_time=0.0; act=0.0, slots...)
 ````
@@ -438,12 +476,14 @@ function add_chunk!(memory::Declarative, cur_time=0.0; act=0.0, slots...)
 end
 
 """
-**add_chunk!** new chunk to declarative memory or updates existing chunk with new use
+**add_chunk!**
+
+Adds a new chunk to declarative memory or updates existing chunk with new use
 * `memory`: declarative memory object
 * `cur_time`: current time, default = 0.0
 * `slots`: optional keyword arguments corresponding to slot-value pairs, e.g. name=:Bob
 
-Function Signature
+**Function Signature**
 ````julia
 add_chunk!(actr::ACTR, cur_time=0.0; request...)
 ````
@@ -451,11 +491,13 @@ add_chunk!(actr::ACTR, cur_time=0.0; request...)
 add_chunk!(actr::ACTR, cur_time=0.0; request...) = add_chunk!(actr.declarative, cur_time; request...)
 
 """
-**get_chunks** returns all chunks that matches a set criteria
+**get_chunks** 
+
+Returns all chunks that matches a set criteria
 * `memory`: vector of chunk objects
 * `args`: optional keyword arguments corresponding to critiria for matching chunk
 
-Function Signature
+**Function Signature**
 ````julia
 get_chunks(memory::Vector{<:Chunk}; args...)
 ````
@@ -466,12 +508,14 @@ function get_chunks(memory::Vector{<:Chunk}; args...)
 end
 
 """
-**get_chunks** returns all chunks that matches a set criteria
+**get_chunks** 
+
+Returns all chunks that matches a set criteria
 * `memory`: vector of chunk objects
 * `funs`: a list of functions
 * `args`: optional keyword arguments corresponding to critiria for matching chunk
 
-Function Signature
+**Function Signature**
 ````julia
 get_chunks(memory::Vector{<:Chunk}, funs...; args...)
 ````
@@ -482,11 +526,13 @@ function get_chunks(memory::Vector{<:Chunk}, funs...; args...)
 end
 
 """
-**get_chunks** returns all chunks that matches a set criteria
+**get_chunks** 
+
+Returns all chunks that matches a set criteria
 * `d`: declarative memory object
 * `args`: optional keyword arguments corresponding to critiria for matching chunk
 
-Function Signature
+**Function Signature**
 ````julia
 get_chunks(d::Declarative; args...) 
 ````
@@ -494,11 +540,13 @@ get_chunks(d::Declarative; args...)
 get_chunks(d::Declarative; args...) = get_chunks(d.memory; args...)
 
 """
-**get_chunks** returns all chunks that matches a set criteria
+**get_chunks** 
+
+Returns all chunks that matches a set criteria
 * `a`: an ACTR Object
 * `args`: optional keyword arguments corresponding to critiria for matching chunk
 
-Function Signature
+**Function Signature**
 ````julia
 get_chunks(a::AbstractACTR; args...)
 ````
@@ -506,12 +554,14 @@ get_chunks(a::AbstractACTR; args...)
 get_chunks(a::AbstractACTR; args...) = get_chunks(a.declarative.memory; args...)
 
 """
-**get_chunks** returns all chunks that matches a set criteria
+**get_chunks** 
+
+Returns all chunks that matches a set criteria
 * `d`: declarative memory object
 * `funs`: a list of functions
 * `args`: optional keyword arguments corresponding to critiria for matching chunk
 
-Function Signature
+**Function Signature**
 ````julia
 get_chunks(d::Declarative, funs...; args...)
 ````
@@ -519,12 +569,14 @@ get_chunks(d::Declarative, funs...; args...)
 get_chunks(d::Declarative, funs...; args...) = get_chunks(d.memory, funs...; args...)
 
 """
-**get_chunks** returns all chunks that matches a set criteria
+**get_chunks** 
+
+Returns all chunks that matches a set criteria
 * `a`: an ACTR Object
 * `funs`: a list of functions
 * `args`: optional keyword arguments corresponding to critiria for matching chunk
 
-Function Signature
+**Function Signature**
 ````julia
 get_chunks(a::AbstractACTR, funs...; args...)
 ````
@@ -532,11 +584,13 @@ get_chunks(a::AbstractACTR, funs...; args...)
 get_chunks(a::AbstractACTR, funs...; args...) = get_chunks(a.declarative.memory, funs...; args...)
 
 """
-**first_chunk** returns the first chunk in memory that matches a set of criteria
+**first_chunk** 
+
+Returns the first chunk in memory that matches a set of criteria
 * `memory`: delcarative memory object
 * `args`: optional keyword arguments corresponding to critiria for matching chunk
 
-Function Signature
+**Function Signature**
 ````julia
 first_chunk(memory::Vector{<:Chunk}; args...)
 ````
@@ -553,11 +607,13 @@ function first_chunk(memory::Vector{<:Chunk}; args...)
 end
 
 """
-**first_chunk** returns the first chunk in memory that matches a set of criteria
+**first_chunk** 
+
+Returns the first chunk in memory that matches a set of criteria
 * `memory`: delcarative memory object
 * `args`: optional keyword arguments corresponding to critiria for matching chunk
 
-Function Signature
+**Function Signature**
 ````julia
 first_chunk(memory::Vector{<:Chunk}; args...)
 ````
@@ -565,11 +621,13 @@ first_chunk(memory::Vector{<:Chunk}; args...)
 first_chunk(d::Declarative; args...) = first_chunk(d.memory; args...)
 
 """
-**first_chunk** returns the first chunk in memory that matches a set of criteria
+**first_chunk** 
+
+Returns the first chunk in memory that matches a set of criteria
 * `a`: an ACTR object
 * `args`: optional keyword arguments corresponding to critiria for matching chunk
 
-Function Signature
+**Function Signature**
 ````julia
 first_chunk(a::AbstractACTR; args...)
 ````
@@ -577,13 +635,15 @@ first_chunk(a::AbstractACTR; args...)
 first_chunk(a::AbstractACTR; args...) = first_chunk(a.declarative.memory; args...)
 
 """
-**match** returns a boolean indicating whether a request matches a chunk.
+**match** 
+
+Returns a boolean indicating whether a request matches a chunk.
 False is returned if the slot does not exist in the chunk or the value
 of the slot does not match the request value.
 * `chunk`: chunk object
 * `request`: a NamedTuple of slot value pairs
 
-Function Signature
+**Function Signature**
 ````julia
 match(chunk::Chunk, request)
 ````
@@ -599,14 +659,16 @@ function match(chunk::Chunk, request)
 end
 
 """
-**match** returns a boolean indicating whether a request matches a chunk.
+**match**
+
+Returns a boolean indicating whether a request matches a chunk.
 False is returned if the slot does not exist in the chunk or the value
 of the slot does not match the request value.
 * `chunk`: chunk object
 * `f`: a list of functions such as `!=, ==`
 * `request`: a NamedTuple of slot value pairs
 
-Function Signature
+**Function Signature**
 ````julia
 match(chunk::Chunk, f, request)
 ````
@@ -624,13 +686,15 @@ function match(chunk::Chunk, f, request)
 end
 
 """
-**match** returns a boolean indicating whether a request matches a chunk.
+**match** 
+
+Returns a boolean indicating whether a request matches a chunk.
 False is returned if the slot does not exist in the chunk or the value
 of the slot does not match the request value.
 * `chunk`: chunk object
 * `request`: a NamedTuple of slot value pairs
 
-Function Signature
+**Function Signature**
 ````julia
 match(chunk::Chunk; request)
 ````
@@ -638,14 +702,16 @@ match(chunk::Chunk; request)
 match(chunk::Chunk; request...) = match(chunk, request)
 
 """
-**match** returns a boolean indicating whether a request matches a chunk.
+**match** 
+
+Returns a boolean indicating whether a request matches a chunk.
 False is returned if the slot does not exist in the chunk or the value
 of the slot does not match the request value.
 * `chunk`: chunk object
 * `funs`: a list of functions such as `!=, ==`
 * `request`: a NamedTuple of slot value pairs
 
-Function Signature
+**Function Signature**
 ````julia
 match(chunk::Chunk, funs...; request)
 ````
@@ -653,12 +719,14 @@ match(chunk::Chunk, funs...; request)
 match(chunk::Chunk, funs...; request...) = match(chunk, funs, request)
 
 """
-*get_subset* returns a filtered subset of the retrieval request when partial matching is on.
+*get_subset* 
+
+Returns a filtered subset of the retrieval request when partial matching is on.
 By default, slot values for isa and retrieved must match exactly.
 - `actr`: an ACTR object
 - `request`: a list of keyword values respresenting slot-value pairs.
 
-Function Signature
+**Function Signature**
 ````julia
 get_subset(actr; request...)
 ````
@@ -669,11 +737,13 @@ function get_subset(actr; request...)
 end
 
 """
-**retrieval_request** returns chunks matching a retrieval request.
+**retrieval_request** 
+
+Returns chunks matching a retrieval request.
 * `memory`: declarative memory object
 * `request`: optional keyword arguments corresponding to retrieval request e.g. dog = :fiddo
 
-Function Signature
+**Function Signature**
 ````julia 
 retrieval_request(actr::AbstractACTR; request...)
 ````
@@ -688,11 +758,13 @@ function retrieval_request(actr::AbstractACTR; request...)
 end
 
 """
-**modify!** modifies fields of an object
+**modify!** 
+
+Modifies fields of an object
 * `c`: an object
 * `args`: optional keywords for field and values
 
-Function Signature
+**Function Signature**
 ````julia 
 modify!(c; args...)
 ````
@@ -704,6 +776,24 @@ function modify!(c; args...)
     return nothing
 end
 
+"""
+**modify!** 
+
+Modifies fields of NamedTupled
+* `c`: a NamedTuple
+* `args`: optional keywords for field and values
+
+**Function Signature**
+````julia 
+modify!(c; args...)
+````
+"""
+function modify!(c; args...)
+    for (k,v) in args
+        setfield!(c, k, v)
+    end
+    return nothing
+end
 function modify!(c::NamedTuple; args...)
     for (k,v) in args
         c[k][1] = v
@@ -712,12 +802,14 @@ function modify!(c::NamedTuple; args...)
 end
 
 """
-**retrieve** retrieves a chunk given a retrieval request
+**retrieve** 
+
+Retrieves a chunk given a retrieval request
 * `actr`: an ACT-R object
 * `cur_time`: current time, default 0.0 (use when base level learning is false)
 * `request`: optional keyword arguments representing a retrieval request, e.g. person=:bob
 
-Function Signature
+**Function Signature**
 ````julia
 retrieve(actr::AbstractACTR, cur_time=0.0; request...)
 ````
@@ -737,10 +829,12 @@ function retrieve(actr::AbstractACTR, cur_time=0.0; request...)
 end
 
 """
-**get_max_active** returns the chunk with maximum activation
+**get_max_active** 
+
+Returns the chunk with maximum activation
 * `chunks`: a vector of chunk objects
 
-Function Signature
+**Function Signature**
 ````julia
 get_max_active(chunks)
 ````
@@ -758,13 +852,15 @@ function get_max_active(chunks)
 end
 
 """
-**compute_RT** generates a reaction time for retrieving a chunk based
+**compute_RT** 
+
+Generates a reaction time for retrieving a chunk based
 on the current activation levels of a chunk. If the vector is empty, time for a retrieval failure 
 is returned
 * `actr`: ACTR object
 * `chunk`: a vector that is empty or contains one chunk
 
-Function Signature
+**Function Signature**
 ````julia
 compute_RT(actr, chunk)
 ````
@@ -778,12 +874,14 @@ function compute_RT(actr, chunk)
 end
 
 """
-**compute_RT** generates a reaction time for retrieving a chunk based
+**compute_RT** 
+
+Generates a reaction time for retrieving a chunk based
 on the current activation levels of a chunk.
 * `actr`: ACTR object
 * `chunk`: a chunk
 
-Function Signature
+**Function Signature**
 ````julia
 compute_RT(actr, chunk)
 ````
@@ -794,11 +892,13 @@ function compute_RT(actr, chunk::Chunk)
 end
 
 """
-**get_parm** returns the value of a parameter
+**get_parm** 
+
+Returns the value of a parameter
 * `actr`: ACTR object
 * ` p`: parameter name
 
-Function Signature
+**Function Signature**
 ````julia
 get_parm(actr, p)
 ````
diff --git a/src/Structs.jl b/src/Structs.jl
index fe1da8b..67c8be9 100644
--- a/src/Structs.jl
+++ b/src/Structs.jl
@@ -80,9 +80,7 @@ A declarative memory chunk
 * `act_pm`: partial matching component of activation
 * `act_sa`: spreading activation component of activation
 * `act_noise`: noise component of activation
-* `dynamic`: slot values are mutable (default: false)
-* `slots`: chunk slots. If dynamic, slots are a dictionary. If not dynamic
-(default), chunks are an immutable NamedTuple.
+* `slots`: chunk slot-value pairs
 * `reps`: number of identical chunks. This can be used in simple cases to speed up the code.
 * `recent`: time stamps for k recent retrievals
 * `lags`: lags for recent retrievals (L - recent)
@@ -112,22 +110,30 @@ mutable struct Chunk{T1,T2}
 end
 
 function Chunk(;N=1, L=1.0, time_created=0.0, k=1, act=0.0, recent=[0.0],
-    reps=0, lags=Float64[], dynamic=false, bl=zero(typeof(act)), slots...)
+    reps=0, lags=Float64[], bl=zero(typeof(act)), slots...)
     T = typeof(act)
     act_pm = zero(T)
     act_blc = zero(T)
     act_bll = zero(T)
     act_noise = zero(T)
     act_sa = zero(T)
-    if dynamic
-        slots = Dict(k=>v for (k,v) in pairs(slots))
-        return Chunk(N, L, time_created, k, act, act_blc, act_bll, act_pm, act_sa, act_noise,
-            slots, reps, recent, lags, bl)
-    end
     return Chunk(N, L, time_created, k, act, act_blc, act_bll, act_pm, act_sa, act_noise,
         slots.data, reps, recent, lags, bl)
 end
 
+function Chunk(dynamic::Bool; N=1, L=1.0, time_created=0.0, k=1, act=0.0, recent=[0.0],
+    reps=0, lags=Float64[], bl=zero(typeof(act)), slots...)
+    T = typeof(act)
+    act_pm = zero(T)
+    act_blc = zero(T)
+    act_bll = zero(T)
+    act_noise = zero(T)
+    act_sa = zero(T)
+    slots = Dict(k=>v for (k,v) in pairs(slots))
+    return Chunk(N, L, time_created, k, act, act_blc, act_bll, act_pm, act_sa, act_noise,
+        slots, reps, recent, lags, bl)
+end
+
 Broadcast.broadcastable(x::Chunk) = Ref(x)
 
 abstract type Mod end
diff --git a/src/Utilities/Printing.jl b/src/Utilities/Printing.jl
index 9921677..dc17bf7 100644
--- a/src/Utilities/Printing.jl
+++ b/src/Utilities/Printing.jl
@@ -1,11 +1,13 @@
 using DataFrames
 """
-**print_memory** prints all chunks in declarative memory and returns a DataFrame.
+**print_memory** 
+
+Prints all chunks in declarative memory and returns a DataFrame.
 - `actr`: an ACTR object
 - `fields`: a keyword argument of tuple of symbols of fields to print. See function signature below for default values.
     Pass fields = :all to print all fields.
 
-Function Signature
+**Function Signature**
 ````julia
 print_memory(actr::AbstractACTR; fields=(:slots,:act_blc,:act_bll,:act_pm,:act_sa,:act_noise,:act))
 ````
@@ -16,12 +18,14 @@ function print_memory(actr::AbstractACTR; fields=(:slots,:act_blc,:act_bll,
 end
 
 """
-**print_memory** prints all chunks in declarative memory and returns a DataFrame.
+**print_memory** 
+
+Prints all chunks in declarative memory and returns a DataFrame.
 - `memory`: a declarative memory object
 - `fields`: a keyword argument of tuple of symbols of fields to print. See function signature below for default values.
     Pass fields = :all to print all fields.
 
-Function Signature
+**Function Signature**
 ````julia
 print_memory(memory::Declarative; fields=(:slots,:act_blc,:act_bll,:act_pm,:act_sa,:act_noise,:act))
 ````
@@ -32,12 +36,14 @@ function print_memory(memory::Declarative; fields=(:slots,:act_blc,:act_bll,
 end
 
 """
-**print_memory** prints all chunks in declarative memory and returns a DataFrame.
+**print_memory** 
+
+Prints all chunks in declarative memory and returns a DataFrame.
 - `chunks`: a vector of chunks
 - `fields`: a keyword argument of tuple of symbols of fields to print. See function signature below for default values.
     Pass fields = :all to print all fields.
 
-Function Signature
+**Function Signature**
 ````julia
 print_memory(chunks; fields=(:slots,:act_blc,:act_bll,:act_pm,:act_sa,:act_noise,:act))
 ````
@@ -57,12 +63,14 @@ function print_memory(chunks; fields=(:slots,:act_blc,:act_bll,
 end
 
 """
-**print_chunk** prints the contents of a chunk and returns a DataFrame.
+**print_chunk** 
+
+Prints the contents of a chunk and returns a DataFrame.
 - `chunk`: a chunk
 - `fields`: a keyword argument of tuple of symbols of fields to print. See function signature below for default values.
     Pass fields = :all to print all fields.
 
-Function Signature
+**Function Signature**
 ````julia
 print_chunk(chunk; fields=(:slots,:act_blc, :act_bll,:act_pm,:act_sa,:act_noise,:act))
 ````
diff --git a/src/Utilities/Utilities.jl b/src/Utilities/Utilities.jl
index 9b133af..35f3a5a 100644
--- a/src/Utilities/Utilities.jl
+++ b/src/Utilities/Utilities.jl
@@ -128,11 +128,11 @@ Returns the index of first chunk that matches a set of criteria
 - `chunks`: an array of chunks
 - `criteria`: a set of keyword arguments for slot-value pairs
 
-Function Signature
+**Function Signature**
 ````julia
 find_indices(actr::ACTR; criteria...)
 ````
-## Example
+**Example**
 ````julia
 chunks = [Chunk(animal=:dog), Chunk(animal=:dog), Chunk(animal=cat)]
 find_indices(chunks; animal=:dog)
@@ -154,11 +154,11 @@ Returns the index of first chunk that matches a set of criteria
 - `funs`: a set of functions
 - `criteria`: a set of keyword arguments for slot-value pairs
 
-Function Signature
+**Function Signature**
 ````julia
 find_indices(actr::ACTR; criteria...)
 ````
-## Example
+**Example**
 ````julia
 chunks = [Chunk(animal=:dog), Chunk(animal=:dog), Chunk(animal=cat)]
 find_indices(chunks; animal=:dog)
@@ -167,16 +167,18 @@ find_indices(chunks; animal=:dog)
 find_indices(actr::ACTR, funs...; criteria...) = find_indices(actr.declarative.memory, funs...; criteria...)
 
 """
-**find_indices** returns the index of first chunk that matches a set of criteria
+**find_indices** 
+
+Returns the index of first chunk that matches a set of criteria
 - `chunks`: an array of chunks
 - `funs`: a set of functions
 - `criteria`: a set of keyword arguments for slot-value pairs
 
-Function Signature
+**Function Signature**
 ````julia
 find_indices(actr::ACTR; criteria...)
 ````
-## Example
+** Example**
 ````julia
 chunks = [Chunk(animal=:dog), Chunk(animal=:dog), Chunk(animal=cat)]
 find_indices(chunks; animal=:dog)
@@ -193,7 +195,12 @@ end
 """
 **import_printing** 
 
-Import printing functions `print_chunk` and `print_memory`
+Import printing functions `print_chunk` and `print_memory`.
+
+**Function Signature**
+````julia
+import_printing()
+````
 """
 function import_printing()
     path = pathof(ACTRModels) |> dirname |> x->joinpath(x, "Utilities/")
@@ -206,7 +213,7 @@ end
 Returns array of chunks or visual objects representing iconic memory 
 - `actr`: an ACTR object
 
-Function Signature
+**Function Signature**
 ````julia
 get_iconic_memory(actr)
 ````
@@ -219,7 +226,7 @@ get_iconic_memory(actr) = actr.visual_location.iconic_memory
 Returns array of chunks or visual objects representing all visual objects
 within the simulation
 
-Function Signature
+**Function Signature**
 ````julia
 get_visicon(actr)
 ````
@@ -235,12 +242,12 @@ Returns posterior predictive distribution and optionally applies function to sam
 - `m`: name of module as a symbol
 
 
-Function Signature
+**Function Signature**
 ````julia
 get_buffer(actr, m)
 ````
 
-Example
+**Example**
 ````julia
 get_buffer(actr, :imaginal)
 ````
@@ -256,7 +263,7 @@ Returns posterior predictive distribution and optionally applies function to sam
 - `v`: new value
 
 
-Function Signature
+**Function Signature**
 ````julia
 set_buffer!(actr, m, v)
 ````