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Fig. 1 (A–B) Experience of live prey increases frequency of paramecia captures in a freely swimming environment. (A) Behavioral paradigm: Fish fed paramecia (‘prey-experienced’) or flakes (‘prey-naïve’) at 5 and 6 dpf were given paramecia at 7 dpf (top, timeline). Prey capture performance was assessed by imaging single fish and paramecia (white specks in lower left image) to count pursuits aborted without a capture attempt, failed capture attempts, and successful captures (summary behavior scheme, lower, right). (B) Summary of performance. Raw data (one symbol per fish) and a boxplot of group statistics show that experienced fish have higher frequencies of total pursuits (successful or not, p = 0.003), and successful captures (p = 0.001), but statistically indistinguishable probabilities of transitioning from pursuit to a capture attempt (p = 0.28), or of transitioning from capture attempt to successful capture (p = 0.12). Statistical comparisons used a permutation test (see Materials and methods) with N = 51 each experienced and naïve fish. (C–E) Experience of live prey increases frequencies of prey- capture initiation in semi-immobilized fish. (C) Setup: semi-immobilized fish face a screen on which small moving dots are projected. Tail flicks and eye angle are imaged from above at 250 fps. Alpha is the angle between the point at 8/10ths of tail length from swim bladder, and midline. In green we show an example tail track during presentation of moving dot. (D) Prey-experienced fish (N = 23) have significantly (p = 0.03) greater discriminability index (d’) than prey-naïve fish (N = 25), two-way ANOVA interaction between experience of live prey vs. lack thereof and contrast (see Materials and methods for calculation of d’). (E) At highest contrast, eye convergence rate in prey-experienced fish was significantly (p = 0.005) greater than in prey-naïve fish (# of times fish converged eyes / # of high contrast stimuli at highest contrast). Note high variability in response rate within groups, with experience improving virtual prey capture performance unevenly across fish, similar to Trivedi and Bollmann, 2013; Semmelhack et al., 2014. See also movies Figure 1—video 1 and Figure 1—video 2. Data tables for panels B, D and E in Figure 1—source data 1.