Two experiments examined the role of various cues on children’s performance in a well-known object-displacement task. In this task, children observed a toy rolling down a ramp whose trajectory was occluded by an opaque screen with doors. A barrier was placed along the ramp, behind one of the doors, to stop the toy. The top portion of the barrier was visible above the screen. To search successfully, children had to retrieve the hidden toy by opening the correct door. Previous work had found that the barrier was an ineffective cue among children less than three years of age. According to a landmark-based account, this was because the barrier was only an indirect cue to object location. If a cue directly marked the location, then it would be more likely attended and utilized. This model underscores the spatial relation between cue and the target. Other cue properties are important in so far that they modify this spatial relation. In Experiment 1, a cue’s distance from the target object was manipulated (i.e., short vs. long), but the location marked by the cue was kept constant (i.e., correct door was directly below). The search performances of 24- and 30-month old children were compared under no cue, short-cue/short-door, and long-cue/long-door conditions. Both age groups performed equally well under both cued conditions. In Experiment 2, a cue’s movement (i.e., coincident with the car vs. not coincident with the car) down the ramp was manipulated. The performance of 24- and 30-month old children were compared under attached-direct cue and unattached-direct cue conditions. Both age groups performed well under both conditions. Collectively, the results provide support for the landmark-based account. The spatial relation between cue and target underlies toddlers’ search. Properties of the cue matter to the extent that they impact how well the cue marks its target.

Two experiments examined the role of various cues on children’s performance in a well-known object-displacement task. In this task, children observed a toy rolling down a ramp whose trajectory was occluded by an opaque screen with doors. A barrier was placed along the ramp, behind one of the doors, to stop the toy. The top portion of the barrier was visible above the screen. To search successfully, children had to retrieve the hidden toy by opening the correct door. Previous work had found that the barrier was an ineffective cue among children less than three years of age. According to a landmark-based account, this was because the barrier was only an indirect cue to object location. If a cue directly marked the location, then it would be more likely attended and utilized. This model underscores the spatial relation between cue and the target. Other cue properties are important in so far that they modify this spatial relation. In Experiment 1, a cue’s distance from the target object was manipulated (i.e., short vs. long), but the location marked by the cue was kept constant (i.e., correct door was directly below). The search performances of 24- and 30-month old children were compared under no cue, short-cue/short-door, and long-cue/long-door conditions. Both age groups performed equally well under both cued conditions. In Experiment 2, a cue’s movement (i.e., coincident with the car vs. not coincident with the car) down the ramp was manipulated. The performance of 24- and 30-month old children were compared under attached-direct cue and unattached-direct cue conditions. Both age groups performed well under both conditions. Collectively, the results provide support for the landmark-based account. The spatial relation between cue and target underlies toddlers’ search. Properties of the cue matter to the extent that they impact how well the cue marks its target.

Coral reef fish larvae take an active role in selecting their settlement site and sensory cues may help them to orientate during this process. As settlement is a period of transition through which the majority of individuals do not survive, it is often a focal point for the management of coral reef populations, which are of high conservation concern. In this thesis, I used choice tests and in situ techniques to assess the response of settlement-stage larvae to a range of odour, light and acoustic cues and I found that larvae are more selective in their response to sensory stimuli than previously thought. Micro-habitat odours are not likely to be used during settlement orientation, and odour cues may be used to avoid inappropriate settlement sites. The photopositive behaviour of larval fish is likely to match their spectral sensitivity but this proved difficult to assess in situ because of the high amount of spatial and temporal variation in larval distribution. The positive response of settlement-stage fish to played back reef noise is location specific as well as being highly specific to the reef sound recording. To understand whether it might be the composition of reef sound that drives the selective response of larvae to acoustic cues, I took sound recordings while collecting visual data on fish diversity and the behavioural activity of a sound producing, or soniferous, fish species. I found that the variation in intensity of reef noise matches the activity patterns of a soniferous species, and when reef noise is most intense is when visual estimates on the diversity of the reef fish assemblage are decreased. This information provides the basis for understanding how changes in the reef soundscape may effect larval recruitment and has exciting implications for using sound recordings as a method to monitor coral reefs. Finally, I tested the viability of releasing reared larvae to boost depleted populations and found that collecting and holding settlement-stage fish for a week can increase survival, relative to natural settlement. These data demonstrate that applying our knowledge of the settlement behaviour of coral reef fish will make a significant contribution to developing tools for management.

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