Lashley (1938)發現，若在訓練階段訓練老鼠辨識以明亮度定義的水平和垂直線段，老鼠在測試階段可以辨識排列成水平和垂直方向的點，證實老鼠可以在之前的學習中萃取出方向的訊息，並類推到之前從未見過的新圖形之中。Hebb定義這樣的能力為「知覺類化」，而這樣的能力大多在哺乳類動物身上發現。Srinivasan, Zhang & Rolfe (1993)訓練蜜蜂辨識水平和垂直的實線條紋，發現蜜蜂在測試階段可以辨識排列成水平和垂直方向的點，證實「知覺類化」的能力不只侷限於較高等的哺乳類動物，較低等的有機體如蜜蜂也具有「知覺類化」的能力。
本研究主要目的便是探討黑腹果蠅是否也擁有「知覺類化」的能力，我們設計兩種圖形來檢證我們的假設，一是完形律中的連續律，二是開放和封閉的圖形。本研究利用果蠅具有趨光性的天性，以嫌惡制約的方式，在黑暗的環境中以類似T形管的儀器訓練並測試果蠅辨識由黑底白字構成的不同圖形。實驗一的結果顯示，在訓練階段被訓練以辨識明亮度定義的十字和圓圈的果蠅，在測試階段中可以顯著的辨識以完型律中的連續律定義所構成的十字和圓圈，反之亦然。而輔助的實驗也說明，這樣的結果並非是因為果蠅無法辨識由明亮度定義或連續律定義所構成的圖形，或是對某特定圖形具有天生的偏好所造成的。實驗二的結果顯示，在訓練階段訓練果蠅辨識封閉的和開放的圓圈，在測試階段中，果蠅也可以顯著的辨識封閉的和開放的三角形。所以，綜合兩個實驗的結果來看，本研究支持黑腹果蠅可以學習辨識簡單的圖形，並類化到新的辨識情況之中。因此黑腹果蠅具有Donald Hebb所說的「知覺類化」能力。
Lashley (1938) showed that rats originally trained with solid-lined vertical and horizontal bars could recognize dotted-lined patterns in the test phase, suggesting that the rats could extract the invariant orientation information. Hebb (1949) recaptured this ability as “perceptual generalization”, which is found mostly in mammals. Srinivasan, Zhang & Rolfe (1993) showed that honeybees trained with solid stripes could successfully distinguish between dotted patterns that were arranged horizontally or vertically. Thus, it demonstrated that “perceptual generalization” exists in lower organisms like honeybees. The purpose of the present study was to explore whether “perceptual generalization” also exist in fruit flies.
We trained and tested fruit flies to discriminate simple shapes by used their phototaxis in T-maze like device (Tully & Quinn,1985), and all of experiments were done in dark room. Results of Experiment 1 showed that when trained with solid-lined shapes, flies displayed significant learning behaviors for the dotted-lined shapes and vice versa. Results of Experiment 2 showed that when trained with one pair of closed vs. open forms, flies exhibited learning transfer for a different pair of closed vs. open forms. In addition, these findings cannot be attributed to a lack of discrimination between the solid-lined and the dotted-lined shapes (or between the open vs. closed forms), or a difference in spontaneous preference. In conclusion, our findings support the notion that Drosophila melanogaster can learn to discriminate simple shapes and generalize them to novel recognition conditions. Thus, the ability of “perceptual generalization” exists in fruit flies.
