Duration estimation of upright and inverted facial stimuli.

The perceived duration of facial stimuli presented in upright and inverted position in the duration ranges of 40 to 470 ms and of 520 to 2030 ms was investigated. In the first duration range the subjective duration of upright faces was longer than the subjective duration of inverted faces for durations of presentation leading to partial recognition, i..e. when upright faces were recognized easier than inverted ones. The difference between the duration estimates decreased when recognition was completed for the facial stimuli in both positions. It is concluded that recognition performance affects perceived duration: easier recognition is accompanied by longer subjective duration. The results obtained in the second duration range confirmed this conclusion. When the faces in both positions were recognized correctly facial position did not affect perceived duration.

Estimating the duration of gratings under masking and nonmasking conditions.

Previous research has shown that the subjective duration of very short time intervals decreases with the increase of spatial frequency (SF) and this effect is supposed to be mediated by an early peripheral component of the persistence process called "retinal persistence". As the retinal components of persistence are very likely to be erased by a mask, we suggest that if retinal persistence underlies SF influence on duration estimation, the introduction of a mask would make subjective duration independent of SF. This inference was tested estimating the duration of presentation of square-wave gratings of equal mean luminance and contrast (85%) and of varying SF under two conditions: with and without a mask. Subjective duration decreased with the increase of SF under both experimental conditions It was concluded that retinal persistence does not underlie the SF effect on brief duration perception. Rather, the apparent contrast of the gratings covarying with SF could account for SF influence on perceived duration.

Upright faces seem to have longer duration of presentation than inverted ones.

Nontemporal variables were shown to influence subjective duration. Some of these variables are known to alter recognition performance. We suggested that the ease of pattern recognition underlies the effect exerted by some nontemporal stimuli characteristics on brief duration estimation. In order to test this assumption, recognition was manipulated by presenting facial stimuli in upright and inverted position. Upright faces are known to be recognized easier than inverted ones. The results showed that the upright faces were judged to last longer than the invprted ones when presented for the same time intervals within the range of 10 to 70 ms. It was concluded that recognition performance might play an essential role in the effect of some nontemporal variables on brief duration perception.

Estimating the duration of briefly presented physiognomic stimuli.

The influence of complex stimuli which are supposed to induce different attitude and emotional effects in the observer on short time interval perception was studied. It is concluded that emotional and/or aesthetical factors do not interfere with short time interval perception.

Spatial frequency, contrast and duration estimation.

Duration estimation of square-wave gratings presented for "short" (up to 150 ms) and "long" (above 190 ms) time intervals was studied. The spatial frequency (SF) of the gratings with equal mean luminance and contrast 85% varied from 0.7 to 12 c/deg. Duration estimates were assessed by the method of magnitude estimation. For brief presentations only the duration of high SF gratings was subjectively shorter than the duration of low SF gratings. It was shown that the apparent contrast of the square-wave gratings decreased with the increase of SF. In an experiment on duration estimation of patterns of different contrast it was demonstrated that duration estimates increased with increasing contrast for short presentations only. The apparent contrast of the gratings covarying with SF was supposed to underlie SF influence on short duration estimation. The assumption about different mechanisms operating in short and long duration perception was supported by the results.

In search of paintings influence on time judgement.

The influence of paintings on short time interval perception was studied. Three methods for time estimation were tested: direct scaling and two modifications of the method of reproduction – with and without simultaneous presentation of the painting whose duration was, reproduced. The results show that short time interval perception is influenced by such complex stimuli as paintings. The motor reproduction with simultaneous presentation of the visual stimulus was the most effective in revealing the influence of paintings on short time interval perception.