Browsing by Author "Peters, Susan"
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Item Open Access Comparison of categorical color perception in two Estrildid finches(The American Naturalist) Caves, Eleanor M; Green, Patrick A; Zipple, Matthew N; Bharath, Dhanya; Peters, Susan; Johnsen, Sönke; Nowicki, StephenItem Open Access Developmental Stress, Song-Learning, and Cognition(INTEGRATIVE AND COMPARATIVE BIOLOGY, 2014-10) Peters, Susan; Searcy, William A; Nowicki, StephenItem Open Access Influence of visual background on discrimination of signal-relevant colours in zebra finches (Taeniopygia guttata).(Proceedings. Biological sciences, 2022-06) Davis, Alexander; Zipple, Matthew N; Diaz, Danae; Peters, Susan; Nowicki, Stephen; Johnsen, SönkeColour signals of many animals are surrounded by a high-contrast achromatic background, but little is known about the possible function of this arrangement. For both humans and non-human animals, the background colour surrounding a colour stimulus affects the perception of that stimulus, an effect that can influence detection and discrimination of colour signals. Specifically, high colour contrast between the background and two given colour stimuli makes discrimination more difficult. However, it remains unclear how achromatic background contrast affects signal discrimination in non-human animals. Here, we test whether achromatic contrast between signal-relevant colours and an achromatic background affects the ability of zebra finches to discriminate between those colours. Using an odd-one-out paradigm and generalized linear mixed models, we found that higher achromatic contrast with the background, whether positive or negative, decreases the ability of zebra finches to discriminate between target and non-target stimuli. This effect is particularly strong when colour distances are small (less than 4 ΔS) and Michelson achromatic contrast with the background is high (greater than 0.5). We suggest that researchers should consider focal colour patches and their backgrounds as collectively comprising a signal, rather than focusing on solely the focal colour patch itself.Item Open Access Long-distance dependencies in birdsong syntax.(Proceedings. Biological sciences, 2022-01) Searcy, William A; Soha, Jill; Peters, Susan; Nowicki, StephenSongbird syntax is generally thought to be simple, in particular lacking long-distance dependencies in which one element affects choice of another occurring considerably later in the sequence. Here, we test for long-distance dependencies in the sequences of songs produced by song sparrows (Melospiza melodia). Song sparrows sing with eventual variety, repeating each song type in a consecutive series termed a 'bout'. We show that in switching between song types, song sparrows follow a 'cycling rule', cycling through their repertoires in close to the minimum possible number of bouts. Song sparrows do not cycle in a set order but rather vary the order of song types from cycle to cycle. Cycling in a variable order strongly implies long-distance dependencies, in which choice of the next type depends on the song types sung over the past cycle, in the range of 9-10 bouts. Song sparrows also follow a 'bout length rule', whereby the number of repetitions of a song type in a bout is positively associated with the length of the interval until that type recurs. This rule requires even longer distance dependencies that cross one another; such dependencies are characteristic of more complex levels of syntax than previously attributed to non-human animals.Item Open Access Variation in vocal production learning across songbirds(Philosophical Transactions of the Royal Society B: Biological Sciences) Searcy, William; Soha, Jill; Peters, Susan; Nowicki, Stephen