Sources of visual interference in delayed matching-to-sample with pigeons

Area of Science:

• Animal Cognition
• Behavioral Neuroscience
• Visual Memory

Background:

• Previous research suggested retroactive interference in pigeons depends on illumination changes.
• The prevailing view posited that any change in light intensity during the delay interval disrupts memory.

Purpose of the Study:

• To investigate the effect of houselight illumination changes during delay intervals on pigeons' identity matching performance.
• To challenge the existing theory on retroactive interference in pigeons concerning illumination levels.

Main Methods:

• Two experiments trained pigeons on an identity matching task with line orientations.
• Pigeons were trained under two conditions: continuous houselight or no houselight.
• Testing involved presenting consistent or opposite lighting conditions during the delay interval.

Main Results:

• Pigeons trained with no houselight showed significant, lasting disruption when the light was turned on during the delay.
• Pigeons trained with the houselight on experienced moderate, temporary disruption when the light was turned off during the delay.
• Results contradict the notion that retroactive interference is solely a function of illumination change.

Conclusions:

• Sustained retroactive interference in pigeons, similar to monkeys, occurs primarily when illumination levels increase during the delay.
• The direction of illumination change (increase vs. decrease) significantly impacts memory disruption.
• Illumination increase during the delay interval is a critical factor for substantial retroactive interference in pigeons.