Recognition of micro‐scale deformation structures in glacial sediments – pattern perception, observer bias and the influence of experience

Abstract

It is a scientist's mission to try to remain unbiased. However, certain factors play a role in scientific analyses that are not controlled by conscious thought. These factors are potentially very important in areas of science where interpretations are based on a scientist's ability to identify patterns or structures. One such area is the micromorphology of glacial sediments. In this paper we investigate the role of an analyst's experience in relation to pattern perception with specific reference to turbate microstructures in glacial diamictons. An experiment was conducted on 52 participants, which demonstrated that, as may be expected, more experienced (glacial) micromorphologists tend to exhibit a higher sensitivity‐to‐signal, but that complete novices, if given clear instructions, can reach levels of sensitivity similar to those of experts. It also showed, perhaps more surprisingly, that response bias does not decrease with experience. We discuss psychological factors, such as the drive for success and consistency, that may have contributed to these results and investigate their possible implications in the micromorphological analysis and interpretation of glacial sediments.

Micromorphology of diamicton affected by iceberg-keel scouring, Scoresby Sund, East Greenland

“…Leighton et al, 2012;Lea and Palmer, 2014;Bendle et al, 2015), but the information that has been gleaned from thin sections of un-consolidated sediments in this and other investigations (see Figs. 7-9), including human-made materials such as concrete and mortar (Menzies et al, 2010;van der Meer and Menzies, 2011 -and references within), is undeniable.…”

Micromorphological evidence of liquefaction, injection and sediment deposition during basal sliding of glaciers

“…However, the development of such structures can be strongly lithologically controlled (e.g. microshears defined by a unistrial plasmic will only form in clay-rich sediments) and their identification is considered to be qualitative and potentially subjective (Leighton et al, 2012;Neudorf et al, 2013). As a result a reliable method of estimating shear strain from thin sections of deformed glacial sediments is yet to be established.…”

Subglacial environments – Introduction

“…Finally, the Leighton et al . () paper takes a longer, almost philosophical, view of microstructure identification in morphological analyses.…”

“…In the paper by Kehew et al (2013), the origin of tunnel valleys along the southern margin of the Laurentide Ice Sheet is examined. Finally, the Leighton et al (2013) paper takes a longer, almost philosophical, view of microstructure identification in morphological analyses. Vaughan-Hirsch et al (2013) bring a fresh perspective to the question of the transport and emplacement of rafted sediment units that led to glaciotectonization in the West Runton area of Norfolk, England.…”

“…In the paper by Leighton et al (2013), the recognition that experience and expertise are still of value is heartening. By investigating how researchers analyse and recognize patterns as microstructures, Leighton et al have made a major contribution to the science of micromorphology.…”