function[residual] = evaluate_model(obj, varargin)

y = obj.deconvolution.input';

slope = varargin{1}(1);
params = varargin{1}(2:end);

x = obj.prf_convolve(obj.stick_model(params),slope);

plot(y, 'k'); hold on; plot(x, 'r-');drawnow; hold off;

residual = sum((y - x).^2);