The influence of image characteristics on image recognition: a comparison of photographs and line drawings

Abstract

Background: Photographs provide more information including colour, luminance, texture, and shading cues compared to line drawings. There is evidence that these additional cues facilitate image recognition in individuals with and without neurological deficits. Black-and-white line drawings and colour photographs are commonly used with individuals with aphasia in evaluation and treatment. Eye tracking provides an opportunity to assess the influence of these different image types on object recognition processes without relying on verbal responses.Aims: The purpose of this study was to determine whether differences in object recognition of photographs and line drawings were observed using eye-tracking measures. Specific goals were to compare the influence of (a) image type of the same target image presented as colour photograph and black-and-white line drawing and (b) degree of colour diagnosticity (high-colour diagnostic natural objects and low-colour diagnostic human-made objects) in multiple-choice image displays on language-mediated eye movements in language-normal adults.Methods & Procedures: Eye movements of 19 participants were recorded while they viewed 66 multiple-choice image displays of colour photographs and black-and-white line drawings presented with a verbal stimulus. Target images included high-colour diagnostic natural objects and low-colour diagnostic human-made objects.Outcomes & Results: Participants allocated significantly greater proportions of fixation duration and first-pass gaze duration to the photographs compared to line drawings. No significant differences were observed for colour diagnosticity differences within the colour or the black-and-white line drawing displays.Conclusions: Eye tracking indexed significant differences in fixation duration allocated to target images in displays that only differed with respect to image type and colour, and were otherwise carefully controlled for shape, size, orientation, and content conveyed. Results suggest that language-normal participants’ object recognition was facilitated by colour photographs compared to line drawings, highlighting the clinical relevance and the need for research of image design for clinical use with individuals with neurological impairments.