This study attempted to discriminate between 2 theories about strategies 5s use when trying to remember a linear ordering. Rating-scale theory argues that 5s represent the items to be learned as points along an imaginary spatial continuum. End-term anchoring theory suggests that serial orderings are learned from the end points inward. A scaling analysis of proportions correct suggested that neither theory alone is sufficient. The 5s apparently represented ordering information along 2 dimensions, the first representing the distance between items on the imaginary continuum and the second representing the distance of the items from the center of the ordering.

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Sounds were produced by the topmouth minnow Pseudorasbora parva, a common Eurasian cyprinid, during feeding but not during intraspecific interactions. Feeding sounds were short broadband pulses with main energies between 100 and 800 Hz. They varied in their characteristics (number of single sounds per feeding sequence, sound duration and period, and sound pressure level) depending on the food type (chironomid larvae, Tubifex worms and flake food). The loudest sounds were emitted when food was taken up at the water surface, most probably reflecting 'suctorial' feeding. Auditory sensitivities were determined between 100 and 4000 Hz utilizing the auditory evoked potentials recording technique. Under laboratory conditions and in the presence of natural ambient noise recorded in Lake Neusiedl in eastern Austria, best hearing sensitivities were between 300 and 800 Hz (57 dB re 1 mPa v. 72 dB in the presence of ambient noise). Threshold-to-noise ratios were positively correlated to the sound frequency. The correlation between sound spectra and auditory thresholds revealed that P. parva can detect conspecific sounds up to 40 cm distance under ambient noise conditions. Thus, feeding sounds could serve as an auditory cue for the presence of food during foraging.

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