Two possible modes of memory trace reproduction

The current study tested spatial memory in 8 adult domestic cats using a spatial delayed response ("DR") memory task. Two existing different variants of that task were used by us in 8 adult domestic cats. One group of 4 cats was tested in the direct variant ("DDR"), while other group of 4 cats was trained to perform indirect variant ("IDDR"). DDR was based on the visual perception of baited food wells located in different places of large room which was rich of distal landmarks; testing of DDR proceeded initially with short delay intervals (minutes) followed after attainment of correct performance criterion (80% of correct responses during two consecutive days, each encompassing 20 trials of DDR), by long delays including one hour. In parallel other four cats were tested in NDDR situation. In that case before memory testing in cats was established quite strong (100% correct) visual discrimination of two different visual stimuli of the "go left - go right" type. Afterwards actual testing of IDDR was issued just with the same program of different delay presentations as was used in preceding DDR situation. Results obtained convinced us, that results of two different methods of DR testing might be explained by different modes of trace retrieval (reproduction) from the visuospatial memory stores - one working in DDR is based on the "cue recall" aided by distal landmarks, presented in DDR situations, and the other working in NDDR based on the "cue recognition" aided by visual discrimination of visual conditioned stimuli.