title: In search of rules behind environmental framing; the case of head pitch.
abstract: BACKGROUND
  Whether, and how, animals move requires them to assess their environment to determine the most appropriate action and trajectory, although the precise way the environment is scanned has been little studied. We hypothesized that head attitude, which effectively frames the environment for the eyes, and the way it changes over time, would be modulated by the environment.
  
  
  METHODS
  To test this, we used a head-mounted device (Human-Interfaced Personal Observation platform - HIPOP) on people moving through three different environments; a botanical garden ('green' space), a reef ('blue' space), and a featureless corridor, to examine if head movement in the vertical axis differed between environments. Template matching was used to identify and quantify distinct behaviours.
  
  
  CONCLUSIONS
  The data on head pitch from all subjects and environments over time showed essentially continuous clear waveforms with varying amplitude and wavelength. There were three stylised behaviours consisting of smooth, regular peaks and troughs in head pitch angle and variable length fixations during which the head pitch remained constant. These three behaviours accounted for ca. 40 % of the total time, with irregular head pitch changes accounting for the rest. There were differences in rates of manifestation of behaviour according to environment as well as environmentally different head pitch values of peaks, troughs and fixations. Finally, although there was considerable variation in head pitch angles, the peak and trough values bounded most of the variation in the fixation pitch values. It is suggested that the constant waveforms in head pitch serve to inform people about their environment, providing a scanning mechanism. Particular emphasis to certain sectors is manifest within the peak and trough limits and these appear modulated by the distribution of the points where fixation, interpreted as being due to objects of interest, occurs. This behaviour explains how animals allocate processing resources to the environment and shows promise for movement studies attempting to elucidate which parts of the environment affect movement trajectories.
authors.affiliation: Department of Geography, College of Science, Swansea University, Singleton Park, Swansea, SA2 8PP Wales UK.
authors.forename: Gwendoline Ixia
authors.identifier: 0000-0002-3868-5581
authors.initials: GI
authors.lastname: Wilson
authors.affiliation: Computer Science, College of Science, Swansea University, Singleton Park, Swansea, SA2 8PP Wales UK.
authors.forename: Brad
authors.initials: B
authors.lastname: Norman
authors.affiliation: ECOCEAN Inc, 102/72 Marine Terrace, Fremantle, WA 6160 Australia.
authors.forename: James
authors.initials: J
authors.lastname: Walker
authors.affiliation: Swansea Lab for Animal Movement, Biosciences, College of Science, Swansea University, Singleton Park, Swansea, SA2 8PP Wales UK.
authors.forename: Hannah J
authors.initials: HJ
authors.lastname: Williams
authors.affiliation: College of Engineering, Swansea University, Singleton Park, Swansea, SA2 8PP Wales UK.
authors.forename: M D
authors.initials: MD
authors.lastname: Holton
authors.affiliation: Department of Geography, College of Science, Swansea University, Singleton Park, Swansea, SA2 8PP Wales UK.
authors.forename: D
authors.initials: D
authors.lastname: Clarke
authors.affiliation: Swansea Lab for Animal Movement, Biosciences, College of Science, Swansea University, Singleton Park, Swansea, SA2 8PP Wales UK.
authors.forename: Rory P
authors.initials: RP
authors.lastname: Wilson
keywords: Daily Diary; Environmental framing; HIPOP; Head movement