(a) Degrees of convergence High convergence Cones Neural signals Retinal ganglion cell Action potentials Incoming light Firing rates High Moderate Low + Baseline Moderate convergence No convergence Low firing rate 11 (b) Spatial summation Moderate firing rate (c) Acuity High convergence, low acuity No convergence, high acuity Same signal sent Different patterns of signals into optic nerve sent into optic nerve High firing rate Region: Finger tip Distance: 2mm Region: Palm Distance: 2mm Region: Back Distance: 2mm Number of Number of Number of points points points applied by applied by applied by researcher researcher researcher 2 1 2 1 2 1 Was there two Answer: 2 0 Was Answer: 0 1 Was Answer: 0 0 Yes, there there Yes, there there Yes, there is two two is two two is two points? points points? points points? points Answer: 1 2 Answer: 3 1 Answer: 3 2 No, there No, there No, there is one is one is one point Distance: 5mm point point Distance: 5 mm Distance: 10mm Number of Number of Number of points points points applied by applied by applied by researcher researcher researcher 2 1 2 1 2 1 Was Answer: 2 1 Was Answer: 2 0 Was Answer: 0 0 there Yes, there there Yes, there there Yes, there two is two two is two two is two points? points points? points points? points Answer: 0 2 No, there is one point Answer: 1 2 Answer: 3 2 No, there No, there is one point is one Distance: 8mm Distance: 10mm point Distance: 20mm Number of Number of Number of points points points applied by applied by applied by researcher researcher researcher 2 1 2 1 2 1 Was Answer: 3 0 there Yes, there Was there Answer: 3 0 Yes, there Was there Answer: Yes, there 2 0 two is two two is two two is two points? points points? points points? points Answer: No, there is one point 0 2 Answer: No, there is one point 0 2 Answer: No, there is one point 1 2