Halkiopoulos, later a doctoral student of Eysenck, carried out this research while he was a psychology undergraduate at UCL, under the supervision of Professor N.F.
He introduced an attentional probe paradigm, which he initially used in the auditory modality to assess attentional biases to threatening auditory information, when threatening and non-threatening information was presented simultaneously to both ears in a dichotic listening task ([1][2][3]).
Halkiopoulos demonstrated attentional biases by measuring reaction times to auditory probes following neutral and emotional words in the attended and unattended channels.
This method was subsequently used in the visual modality by MacLeod, Mathews and Tata (1986) in what came to be known as the dot-probe paradigm.
https://doi.org/10.31219/osf.io/6y3d8 Despite Professor Mathews's (as well as others') clear identification of Halkiopoulos as the originator of the dot-probe paradigm, this pioneering technique has often been misattributed in the academic literature.
For example, the following correction note by Professor Michael Eysenck is only one of several appearing on the publisher Taylor & Francis' bookseller sites.
"Correction notice: In chapter 4, on pages 70-71, Christos Halkiopoulos should have been credited for his role as the inventor of the Dot Probe Paradigm and for the design and execution of the experiment discussed in Eysenck, M. W. (1991 a).
https://doi.org/10.31234/osf.io/jvx68 "In many cases, the dot-probe paradigm is used to assess selective attention to threatening stimuli in individuals diagnosed with anxiety disorders.
Attention biases toward positive stimuli have been associated with a number of positive outcomes such as increased social engagement, increased prosocial behavior, decreased externalizing disorders, and decreased emotionally withdrawn behavior.
Quicker reaction time to the dot when it occurs in the previous location of a threatening stimulus is interpreted as vigilance to threat.
Researchers have recently begun using a modified version of the dot-probe task to retrain the attentional bias.