Do reef fish, variola louti and scarus niger, perform amodal completion? Evidence from a field study.

In terms of visual perception, coral reefs are structurally complex habitats. Therefore, visual stimuli that invoke territorial behavior in fish, causing them to respond to potential intruders and competitors, may be fragmented. Amodal completion was recently shown in a fish species. Here, we presented a mirror covered by occluders, with different squared openings arranged in a vertical or a horizontal broken line or a checkerboard formation, within their natural territories in the reef. Single small openings in the occluders did not trigger an attack on the reflected image, while specific configurations of them did so, suggesting that fish recognized an intruder in the fragmented image. The results suggest the use of amodal completion by fish although other possibilities cannot be rejected. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Effects of dorsal and ventral vertical lobe electrolytic lesions on spatial learning and locomotor activity in Sepia officinalis.

This study aims to analyze the effects of electrolytic lesion, restricted to either the ventral or the dorsal parts of the vertical lobe (VL), on the behavior of cuttlefish (Sepia officinalis). Two behavioral tests were performed on sham-operated and lesioned cuttlefish: assessment of locomotor activity in an open field and determination of spatial learning abilities in a T maze. The results showed that ventral lesions of the VL led to marked impairment in the acquisition of spatial learning, whereas dorsal lesions of the VL increased locomotor activity in the open field and impaired long-term retention of spatial learning. This study establishes for the first time the existence of distinct functions in the ventral and the dorsal parts of the VL in cephalopods. (PsycINFO Database Record (c) 2010 APA, all rights reserved)