An automatic stack feeder comprising: a shingulating device configured to receive a stack of articles and to produce a positively lapped stack of articles; a plurality of picking devices (1410, 2010) configured to pick one or more articles from the positively lapped stack of articles and to produce one or more singulated articles; wherein each of the plurality of picking devices (1410, 2010) is located in a respective picking zone, each respective picking zone includes a picking device (1410, 2010) and an anti-doubling device (1424, 2022A, 2022B) opposite the picking device (1410, 2010), the anti-doubling device (1424, 2022A, 2022B) configured to prevent more than one article at a time from being picked from the positively lapped stack of articles, wherein each of the plurality of picking devices (1410, 2010) comprises: a vertically oriented perforated belt (1044, 1706) having one or more openings in its surface, the perforated belt (1044, 1706) configured to be driven by a motor; a vacuum manifold located adjacent to the perforate belt (1044, 1706); a vacuum unit configured to apply suction through the vacuum manifold, wherein the vacuum manifold is configured to apply the suction through the one or more openings in the surface of the perforated belt (1044, 1706); and a vacuum valve configured to control the amount of suction applied by the vacuum unit to the vacuum manifold; wherein the anti-doubling device (1424, 2022A, 2022B) includes: a presence sensor configured to detect a first article; an edge detector sensor positioned upstream from the presence sensor and configured to detect an edge of a second article; and a vacuum unit configured to apply suction to the second article when the presence sensor detects the first article during a time period in which the edge detector detects the edge of the second article; and one or more synchronization devices configured to deliver the one or more singulated articles to a sorter window. a shingulating device configured to receive a stack of articles and to produce a positively lapped stack of articles; a plurality of picking devices (1410, 2010) configured to pick one or more articles from the positively lapped stack of articles and to produce one or more singulated articles; wherein each of the plurality of picking devices (1410, 2010) is located in a respective picking zone, each respective picking zone includes a picking device (1410, 2010) and an anti-doubling device (1424, 2022A, 2022B) opposite the picking device (1410, 2010), the anti-doubling device (1424, 2022A, 2022B) configured to prevent more than one article at a time from being picked from the positively lapped stack of articles, wherein each of the plurality of picking devices (1410, 2010) comprises: a vertically oriented perforated belt (1044, 1706) having one or more openings in its surface, the perforated belt (1044, 1706) configured to be driven by a motor; a vacuum manifold located adjacent to the perforate belt (1044, 1706); a vacuum unit configured to apply suction through the vacuum manifold, wherein the vacuum manifold is configured to apply the suction through the one or more openings in the surface of the perforated belt (1044, 1706); and a vacuum valve configured to control the amount of suction applied by the vacuum unit to the vacuum manifold; a vertically oriented perforated belt (1044, 1706) having one or more openings in its surface, the perforated belt (1044, 1706) configured to be driven by a motor; a vacuum manifold located adjacent to the perforate belt (1044, 1706); a vacuum unit configured to apply suction through the vacuum manifold, wherein the vacuum manifold is configured to apply the suction through the one or more openings in the surface of the perforated belt (1044, 1706); and a vacuum valve configured to control the amount of suction applied by the vacuum unit to the vacuum manifold; wherein the anti-doubling device (1424, 2022A, 2022B) includes: a presence sensor configured to detect a first article; an edge detector sensor positioned upstream from the presence sensor and configured to detect an edge of a second article; and a vacuum unit configured to apply suction to the second article when the presence sensor detects the first article during a time period in which the edge detector detects the edge of the second article; and a presence sensor configured to detect a first article; an edge detector sensor positioned upstream from the presence sensor and configured to detect an edge of a second article; and a vacuum unit configured to apply suction to the second article when the presence sensor detects the first article during a time period in which the edge detector detects the edge of the second article; and one or more synchronization devices configured to deliver the one or more singulated articles to a sorter window.