Abstract
Illusory line motion (ILM) refers to the perception of motion in a line that is, in fact, presented in full at one time. One form of this illusion (flashILM) occurs when the line is presented between two objects following a brief luminance change in one of them and flashILM is thought to result from exogenous attention being captured by the flash. Exogenous attention fades with increasing delays, which predicts that flashILM should show a similar temporal pattern. Exogenous attention appears to follow flashILM to become more or less equally distributed along the line.The current study examines flashILM in order to test these predictions derived from the attentional explanation for flashILM and the results were consistent with them. The discussion then concludes with an exploratory analysis approach concerning states of consciousness and decision making and suggests a possible role for attention.
Highlights
Illusory line motion (ILM) refers to the perception of motion in a bar that is presented all at once.ILM can occur under a number of different conditions
The illusory motion that arises in flash ILM, transformational apparent motion (TAM), and polarised gamma motion (PGM) can be quantified in a single value referred to as ILMarea
ILMarea was analysed in a within-subjects analysisof ofvariance variance (ANOVA) with delay as a factor, which showed a main effect of delay (F(3,69) = 78.121, p < 0.001, pH0|D < 0.01, MSE = 0.577, ηp 2 = 0.773; M = 3.946, 1.743, 1.314, 0.851, for delays 16.7, 166.7, 316.7, and 466.7 ms, respectively, with single sample t(23) = 14.67, 10.53, 6.21, and 4.01, all p < 0.01 and pH0|D < 0.01 all very strong evidence against the null hypothesis, respectively)
Summary
Illusory line motion (ILM) refers to the perception of motion in a bar that is presented all at once.ILM can occur under a number of different conditions. Participants respond by indicating the direction in which the bar appears to move, scoring rightward responses as +1 and leftward as −1, and averaging these “percept scores” over a number of presentations. This scoring results in a measure akin to a guess corrected accuracy. The percept scores are plotted as a series over the real motion separately for left and right side inducers, and the area between these series can be used to quantify a participant’s illusion (see [11] for more information) This measure is highly stable, and participants who show a large illusion in one condition will show a large illusion in another condition provided both conditions reflect the same underlying illusion. TAM can arise when the boxes and bar match based upon colour or based upon size, and the ILMarea measures for these two illusions are highly correlated [6] as both are thought to reflect the tracking of objects
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