Dr Sam Strong

Lecturer, Optometry Aston University

  • Birmingham

Dr Strong's main area of research interest is visual perception, with a focus on motion processing related to optic flow.

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Aston University study reveals the illusion of ‘dazzle’ paint on World War I battleships

The Zealandia in wartime dazzle paint. Image: Australian National Maritime Museum on The Commons Geometric ‘dazzle’ camouflage was used on ships in WWI to confuse enemy onlookers as to the direction and speed of the ship Timothy Meese and Samantha Strong reanalysed historic data from 1919 and found that the ‘horizon effect’ is more effective for confusion When viewing a ship at distance, it often appears to be travelling along the horizon, regardless of its actual direction of travel – this is the ‘horizon effect’. A new analysis of 105-year-old data on the effectiveness of ‘dazzle’ camouflage on battleships in World War I by Aston University researchers Professor Tim Meese and Dr Samantha Strong has found that while dazzle had some effect, the ‘horizon effect’ had far more influence when it came to confusing the enemy. During World War I, navies experimented with painting ships with ‘dazzle’ camouflage – geometric shapes and stripes – in an attempt to confuse U-boat captains as to the speed and direction of travel of the ships and make them harder to attack. The separate ‘horizon effect’ is when a person looks at a ship in the distance, and it appears to be travelling along the horizon, regardless of its actual direction of travel. Ships travelling at an angle of up to 25° relative to the horizon appear to be travelling directly along it. Even with those at a greater angle to the horizon, onlookers significantly underestimate the angle. Despite widespread use of dazzle camouflage, it was not until 1919 that a proper, quantitative study was carried out, by MIT naval architecture and marine engineering student Leo Blodgett for his degree thesis. He painted model ships in dazzle patterns and placed them in a mechanical test theatre with a periscope, like those used by U-boat captains, to measure how much onlookers’ estimations of the ships’ direction of travel deviated from their actual direction of travel. Professor Meese and Dr Strong realised that while the data collected by Blodgett was useful, his methods of experimental design fell short of modern standards. He’d found that dazzle camouflage worked, but the Aston University team suspected that dazzle alone was not responsible for the results seen, cleaned the data and designed new analysis to better understand what it really shows. Dr Strong, a senior lecturer at Aston University’s School of Optometry, said: “It's necessary to have a control condition to draw firm conclusions, and Blodgett's report of his own control was too vague to be useful. We ran our own version of the experiment using photographs from his thesis and compared the results across the original dazzle camouflage versions and versions with the camouflage edited out. Our experiment worked well. Both types of ships produced the horizon effect, but the dazzle imposed an additional twist.” If the errors made by the onlookers in the perceived direction of travel of the ship were entirely due to the ‘twist’ on perspective caused by dazzle paintwork, the bow, or front, of the ship, would always be seen to twist away from its true direction. However, Professor Meese and Dr Strong instead showed that when the true direction was pointing away from the observer, the bow was often perceived to twist towards the observer instead. Their detailed analysis showed a small effect of twist from the dazzle camouflage but a much larger one from the horizon effect. Sometimes these effects were in competition, sometimes in harmony. Professor Meese, a professor of vision science at the School of Optometry, said: “We knew already about the twist and horizon effects from contemporary computer-based work with colleagues at Abertay University. The remarkable finding here is that these same two effects, in similar proportions, are clearly evident in participants familiar with the art of camouflage deception, including a lieutenant in a European navy. This adds considerable credibility to our earlier conclusions by showing that the horizon effect – which has nothing to do with dazzle – was not overcome by those best placed to know better. “This is a clear case where visual perception is more powerful than knowledge. In fact, back in the dazzle days, the horizon effect was not identified at all, and Blodgett's measurements of perceptual bias were attributed entirely to the camouflage, deceiving the deceivers.” Professor Meese and Dr Strong say that more work is required to fully understand how dazzle might have increased perceptual uncertainty of direction and speed but also the geometry behind torpedo-aiming tactics that might have supported some countermeasures. Visit https://doi.org/10.1177/20416695241312316 to read the full paper in i-Perception.

Dr Sam Strong

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Biography

Dr Strong's main area of research interest is visual perception, with a focus on motion processing related to optic flow. She is also interested in how the brain processes visual durations/temporal experience. Currently, she is investigating this through two key strategies:

1) Investigation of motion-sensitive visual areas in the human brain.

These projects aim to identify the functional differences and connections between motion-sensitive visual areas in the human brain (MT/TO-1, MST/TO-2, V3A). This involves the use of neuroimaging (fMRI), neurostimulation (TMS), and behavioural measures (psychophysics).

2) Impact of pathology on perception.

Increases in blur or reduction in contrast can affect perception of moving scenes; these projects investigate the threshold-level perception of individuals with cataracts (with PhD student Ayah Al-Rababah).

Areas of Expertise

Visual Perception
Optic Flow
Visual Durations
Motion Processing
Temporal Experience
Cataracts

Accomplishments

'Best Oral Presentation', AVA Meeting

2018

Silmo Academy Bursary

2017

'Student Travel Award', VSS

2016

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Education

University of Bradford

PhD

Vision Science

2015

University of York

BSc (Hons) Psychology

2012

Media Appearances

Sam Strong

More Than Optics  online

2022-01-05

Sam Strong is a lecturer in Optometry at Aston University, having graduated from the University of Bradford with a PhD in Vision Science in 2015, after initially graduating with a BSc in Psychology from the University of York.

In this episode of More Than Optics, Sam tells Jayshree and Bhavin about how her other passion for illustrating has helped her in the day job, as well as the challenges of teaching online during the pandemic.

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Articles

Transcranial Magnetic Stimulation Mapping for Perceptual and Cognitive Functions

Lesion-to-Symptom Mapping

2022

Transcranial magnetic stimulation (TMS) is a powerful neuroscience technique that provides a mechanism to study causal brain-behavior relationships in both healthy and damaged/diseased brains with a high-degree of both spatial and temporal precision. In this chapter, we take you through the mechanisms of TMS and discuss practical aspects of using TMS for mapping perceptual and cognitive functions in both basic science and clinical contexts.

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Motion perception and the temporal metaphysics of consciousness

Journal of Consciousness Studies

2021

This paper defends a 'punctivist' conception of consciousness from recent attacks by Ian Phillips and Matthew Soteriou. As we intend it, 'punctivism' is the view that a subject's experience over some interval is determined by their experiential states at each instant during it. Phillips and Soteriou both offer ingenious arguments purporting to show that the punctivist is unable to make sense of motion perception; and that only by adopting an 'holistic' conception -- whereby a subject's instantaneous experiences are determined by their experience over the interval -- can we make sense of the puzzles such phenomena pose. We contend that both arguments invoke dubious claims, their proffered solutions come with highly controversial commitments, and, if we take punctivism seriously, it is difficult to see why the so-called puzzles should be puzzling in the first place. A punctivist model of motion perception is proposed in response, and objections anticipated.

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An enhanced role for right hV5/MT+ in the analysis of motion in the contra-and ipsi-lateral visual hemi-fields Authors Samantha L Strong, Edward H Silson, André D Gouws, A

Behavioural Brain Research

2019

Previous experiments have demonstrated that transcranial magnetic stimulation (TMS) of human V5/MT+, in either the left or right cerebral hemisphere, can induce deficits in visual motion perception in their respective contra- and ipsi-lateral visual hemi-fields. However, motion deficits in the ipsi-lateral hemi-field are greater when TMS is applied to V5/MT + in the right hemisphere relative to the left hemisphere. One possible explanation for this asymmetry might lie in differential stimulation of sub-divisions within V5/MT + across the two hemispheres. V5/MT + has two major sub-divisions; MT/TO-1 and MST/TO-2, the latter area contains neurons with large receptive fields (RFs) that extend up to 15° further into the ipsi-lateral hemi-field than the former. We wanted to examine whether applying TMS to MT/TO-1 and MST/TO-2 separately could explain the previously reported functional asymmetries for ipsi-lateral motion processing in V5/MT + across right and left cerebral hemispheres. MT/TO-1 and MST/TO-2 were identified in seven subjects using fMRI localisers.

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