Induced false memories of having heard the unspoken: a demonstration.

In a mock public survey situation, many students who had been led to expect to be asked to name their academic majors or home towns later declared that they had been asked for that information even though they had not. Such illusory memories were even more common among subjects who had spontaneously volunteered the unasked-for information during the interview. Both results have important implications for reality-monitoring processes and errors.

Rock's cognitive theory of illusory figures: a commentary.

Contrary to a previously published opinion, the 'cognitive' theory of illusory contours is rich in detail and empirical support.

A global factor in the Hermann grid illusion or an artifact?

In the first of the present experiments, subjects were required to estimate the strength of the Hermann grid illusion in grids containing various numbers of intersections even though those grids were not actually presented. The positive relationship found by Wolfe (1984) for real grids was, nevertheless, replicated. It is argued that this suggests that a response bias might have been the source of his effect (although other possibilities are also noted). In addition, in a second experiment, subjects who were not aware of the fact that grid size was being manipulated (i.e., between subjects) showed no consistent effect of that factor, thus supporting the same suggestion.

Cognitively based apparent motion: an extreme case.

An ambiguous figure is used to provide a demonstration of apparent motion in which there is no change in the retinal image or in external space.

On the microgenesis of illusory figures: a failure to replicate.

Reynolds found in 1981 that with increased viewing time of a pattern which may or may not produce illusory contours there were: first, reports of the pattern without an illusory figure; then, at longer exposures, an increase in the frequency with which illusory figures were reported; and then, with still longer exposures, a decrease in such reports if the pattern contained elements which tended to contradict the possibility of such a figure. Unfortunately, however, three attempts to replicate these potentially very important findings--with the aid of substantially improved methodology--consistently failed to do so. It is suggested that this failure, although it is disappointing to those who subscribe to a 'problem solving' explanation of illusory contours, may not constitute a strong refutation of such a theory. Regardless, the purpose in the report is to clarify and rectify the published record concerning this part of the evidential underpinnings of that theory.

The effect of extraneous elements surrounding a Kanizsa-like illusory-figure pattern.

A display in which a Kanizsa-like illusory-figure pattern of three notched circles was accompanied by several other notched circles was found to be relatively ineffective, thus confirming an important, but previously untested, suggestion. This ineffectiveness may have been due to a strengthened tendency of the visual system perceptually to 'explain' each edge of each of the three critical notches as belonging to one of the partial circles themselves, thus tending to preclude any other (ie illusory) 'explanation' of those edges.

Sighting-down and the Poggendorff illusion: a mystery within a mystery.

As reported before, sighting-down one of the diagonal lines on a typical Poggendorff pattern will reduce the illusion even if that situation is only pictorial. But here it is also argued that sighting-down itself requires further understanding.

Illusory contours from pictorially three-dimensional inducing elements.

Illusory-figure patterns which are composed of pictorial elements representing three-dimensional partial disks are sometimes effective and sometimes not. When they are not effective, it is apparently because they contain information that contradicts the presence of an occluding figure and/or because all of the edges within the pattern are seen as edges of various pictured surfaces of the elements.

Outlined elements, regular elements and coincidences in illusory-figure patterns.

When elements in a pattern which would otherwise produce an illusory figure are modified by outlining or by increasing their regularity (in accordance with a proposed measure of the latter quality), the illusory effect is much reduced. Both results reflect the principle that 'coincidences' in a display play little or no role in the process of segmentation when other circumstances tend to force critical edges to 'belong' to individual elements of the display.

Pictorial depth and the Poggendorff illusion.

An informal demonstration is offered, which strongly supports previous contentions that, when the elements of a Poggendorff display appear to be arranged in pictorial space such that the two critical line segments are at different heights, an illusory impression of misalignment may occur. A second pair of demonstrations shows, however, that such a height difference is neither a necessary nor a sufficient cause of the illusion. In addition, the harmful effect of adding certain pictorial elements to the standard Poggendorff pattern requires a new understanding.

Illusory-figure lightness: evidence for a two-component theory.

Physical darkness gradients were introduced into an illusory-figure pattern which were sufficient to eliminate the illusory lightness effect otherwise seen there. Next, such a gradient was left in place along one edge of that figure while the other edges were returned to physical homogeneity with the surround. Rather surprisingly, the physical gradient still present along the unaltered edge was now overwhelmed by illusory lightness. It is argued that this anomaly suggests that illusory-figure lightness may be composed of two additive components, one of which is figure-ground contrast enhancement and the other of which is contingent upon that first component.

Thatcher and the Cheshire cat: context and the processing of facial features.

As has been noted before, a face made gruesome by the inversion of its mouth will not be so perceived when the entire construction is inverted. Results are presented which suggest that this is because the mouth and eye features are evaluated individually (although each feature may influence the evaluation of the other) and the mouth, whether normal or inverted, tends to have its uppermost part assigned as 'top', providing for either a pleasant smiling-mouth expression or a gruesome 'biting-intention' expression. However, the gruesomeness of an inverted mouth is attenuated when eyes are shown below it (producing an inverted smiling face) which suggests that the location of other facial features can also influence the assignments of 'top'.