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Cognition/categorise_medin_schaffer_e...

106 lines
2.9 KiB
Matlab

function categorise_medin_schaffer_expt2()
%Medin & Schaffer (1978) Expt 2
training=[1,1,1,0;
1,0,1,0;
1,0,1,1;
1,1,0,1;
0,1,1,1;
1,1,0,0;
0,1,1,0;
0,0,0,1;
0,0,0,0];
class=[1;1;1;1;1;0;0;0;0];
testing=[1,0,0,1;
1,0,0,0;
1,1,1,1;
0,0,1,0;
0,1,0,1;
0,0,1,1;
0,1,0,0];
Xfeatures=[0,1];
Xclass=[0,1];
%define weights
W{1}=zeros(4,4*length(Xfeatures)+length(Xclass));
%rule 1: if feature 1=1, than class 1
t=[1,0.5,0.5,0.5];
W{1}(1,:)=[code_all(t,Xfeatures),code(1,Xclass)];
%exception: 5th training item
W{1}(2,:)=[code_all(training(5,:),Xfeatures),code(class(5),Xclass)];
%rule 2: if feature 1=0, than class 0
t=[0,0.5,0.5,0.5];
W{1}(3,:)=[code_all(t,Xfeatures),code(0,Xclass)];
%exception: 6th training item
W{1}(4,:)=[code_all(training(6,:),Xfeatures),code(class(6),Xclass)];
W{2}=zeros(4,4*length(Xfeatures)+length(Xclass));
%rule 1: if feature 3=1, than class 1
t=[0.5,0.5,1,0.5];
W{2}(1,:)=[code_all(t,Xfeatures),code(1,Xclass)];
%exception: 4th training item
W{2}(2,:)=[code_all(training(4,:),Xfeatures),code(class(4),Xclass)];
%rule 2: if feature 3=0, than class 0
t=[0.5,0.5,0,0.5];
W{2}(3,:)=[code_all(t,Xfeatures),code(0,Xclass)];
%exception: 7th training item
W{2}(4,:)=[code_all(training(7,:),Xfeatures),code(class(7),Xclass)];
W{3}=[];
for c=0:1
%one prediction neuron for each prototype
ind=find(class==c);
W{3}=[W{3};[code_all(mean(training(ind,:)),Xfeatures),code(c,Xclass)]];
end
for wType=1:length(W)
%normalise weights
W{wType}=bsxfun(@rdivide,W{wType},max(1e-6,sum(W{wType},2)));
[n,m]=size(W{wType})
%simulate categorization expt
for k=1:size(testing,1)
x=[code_all(testing(k,:),Xfeatures),0*Xclass]';
[y,e,r]=dim_activation(W{wType},x);
predict=r(m-(length(Xclass)-1):m)';
category(wType,k)=sum(Xclass.*predict)./sum(predict);
end
end
%plot results
figure(1),clf
axes('Position',[0.16,0.15,0.6,0.6]),
plot(category(1,:),'b-s','LineWidth',2,'MarkerFaceColor','b','MarkerSize',8),hold on
plot(category(2,:),'-d','LineWidth',2,'Color',[0,0.7,0],'MarkerFaceColor',[0,0.7,0],'MarkerSize',8),
plot(category(3,:),'r-o','LineWidth',2,'MarkerFaceColor','r','MarkerSize',8),
axis([0.5,7.5,0,1])
legend(['rule+exception 1 ';
'rule+exception 2 ';
'prototype '],'Location',[0.362,0.85,0.2,0.06]);
hold on, plot([0,10],[0.5,0.5],'k--')
set(gca,'XTick',[1:7],'XTickLabel',[1:7],'FontSize',12)
xlabel('transfer item');ylabel('probability of A')
set(gcf,'PaperSize',[7 8],'PaperPosition',[0.25 0 8 8],'PaperOrientation','Portrait');
print(gcf, '-dpdf','categorise_medin_schaffer_expt2.pdf');
function c=code_all(x,X)
c=[];
for i=1:length(x)
c=[c,code(x(i),X)];
end
function c=code(x,X,precision)
if nargin<3 || isempty(precision)
precision=2;
end
c=zeros(1,length(X));
c=exp(-precision.*(x-X).^2);
c=c./sum(c);