In reading research, a longstanding question is whether word perception is affected by familiar, global visual configurations (Cattell, 1886; Johnson, 1975), in addition to letter-level analysis. Certain findings suggest a role for configural processing. For example, “word shape” features are sometimes sufficient for identification (Beech & Mayall, 2005; Huey, 1908). Words with distinctive outlines are also more efficiently processed parafoveally (McConkie & Rayner, 1975). However, word shape effects are inconsistent (Paap, Newsome, & Noel, 1984) and direct manipulation by cAsE MiXinG has relatively little impact on perception (Besner & Johnston, 1989). On the whole, to the degree that configural processes affect word perception, their effect seems quite small.

Although the literature suggests a minimal role for configural processes in reading, it is important to note that virtually all studies have involved computer-generated words, with letters separated and pristine. As was noted by Barnhart and Goldinger (2010), little research has examined the perception of handwritten words, such as . Relative to synthetic print, letters in handwriting are noisy and ambiguous, and their physical forms are affected by neighboring letters. In perception, as a general rule, when bottom-up cues become less reliable, top-down processing tends to increase (Becker & Killion, 1977). Given handwritten words, configural processes may assume a more prominent role. In the present study, we tested this hypothesis, taking our inspiration from the Thatcher effect in face perception (Thompson, 1980), wherein people cannot adequately appreciate facial feature misorientations when faces are inverted. When the same face is shown in its normal orientation, the inverted eyes and mouth are striking. According to many accounts (e.g., Bartlett & Searcy, 1993), when faces are inverted, configural processes are impaired, which reduces appreciation for the component features (although see Talati, Rhodes, & Jeffery, 2010).

Prior researchers have adapted the Thatcher illusion to examine configural processes in reading. Wong, Twedt, Sheinberg, and Gauthier (2010) asked participants to make same–different judgments for sequentially presented upright and inverted word and nonword pairs that were normal or had been “Thatcherized” by rotating one or two internal letters 180 °, relative to the rest. The researchers observed a robust Thatcher illusion: Discrimination between normal and Thatcherized stimuli was reduced when the stimuli were presented upside-down. Interestingly, the effect was larger for words than for nonwords, and it interacted with word frequency. Both findings suggest that top-down processes superseded the complex bottom-up analysis necessary for successful discrimination of ambiguous low-frequency/nonword items (see Parks, 1983; Rock, 1988).

In two experiments, we evaluated the importance of configural processing in word perception by rotating synthetic and handwritten words 90 ° clockwise or counterclockwise. Lewis (2001) found that RTs to categorize faces as “Thatcherized” or “not Thatcherized” increased gradually as the faces were rotated, suggesting that the configural processing used to recognize upright faces gradually shifts to a component processing strategy with rotation. With words, Koriat and Norman (1985) observed similar increases in recognition time as a consequence of rotation (see also Pashler, Ramachandran, & Becker, 2006). From a working hypothesis that handwritten word perception relies more heavily on configural information, we expected that rotating handwritten exemplars would have a larger perceptual effect, relative to typewritten words.

In preparing our experiments, we immediately noticed a powerful perceptual asymmetry: When handwritten words were rotated clockwise, they were far more difficult to read, relative to those rotated counterclockwise (see Fig. 1), suggesting that rotation interacts with the natural tilt of the handwriting. Whether right- or left-handed, most people produce handwriting with a rightward tilt, as in the upper row of Fig. 1. When these words are rotated clockwise, their natural tilt exaggerates the degree of rotation, whereas it mitigates the effect of counterclockwise rotation. Thus, when words are rotated in a tilt-consistent direction, their constituent letters wind up more inverted, relative to being rotated in the opposite direction. As in the Thatcher illusion, greater inversion reduces appreciation for relations among features. In reading, Jolicœur, Snow, and Murray (1987) studied rotated-letter recognition, using letters from two different fonts, one more familiar than the other. Rotating letters clockwise, they observed a linear increase in recognition times up to 120 ° rotation; this effect was larger for the unfamiliar font. Had they also rotated letters counterclockwise, they might have discovered the perceptual effect at the heart of this article: Their unfamiliar font was Profil, which has a slight rightward tilt, similar to handwriting.

Fig. 1
figure 1

Sample stimuli in right- and left-tilting handwriting and print at the –90 ° and +90 ° orientations. To fully appreciate the perceptual effect, refrain from tilting your head as you read. To experience a reversal of the effect, turn the figure upside-down

Full size image

In a pilot experiment, we showed participants printed and cursive words for 500 ms in the standard orientation, rotated +90 °, or rotated –90 °. All of the items were produced with a common rightward tilt (Fig. 1, upper row). Presuming that configural processing is mainly important for handwritten words, we expected printed word recognition to vary little with rotation. Conversely, we expected rotation to impair handwritten word perception, especially for words rotated clockwise. Indeed, printed words were identified with 90 % accuracy and minimal effects of rotation. Cursive words were identified with 85 % accuracy when displayed horizontally. When the words were rotated counterclockwise, accuracy decreased to 57 %. When they were rotated clockwise, accuracy fell to 31 %.

In a second pilot experiment, we added words from a volunteer whose handwriting has an unusual, leftward tilt (Fig. 1, second row). Hypothesizing that our initial finding reflected direction of tilt, we now expected more errors following counterclockwise rotation. The printed and the right-tilting words replicated the previous results. The left-tilting words were relatively hard to read even when horizontal, with 74 % accuracy. When rotated, the results flipped, relative to right-tilting words: Accuracy was only 8 % for words rotated counterclockwise and 37 % for words rotated clockwise. Together, these pilot studies verified the phenomenological observation (which is easily appreciated in Fig. 1), and motivated the experiments reported next, which included greater stimulus control.

Experiment 1

Our pilot studies suggested that handwritten words elicit greater reliance on configural properties, relative to synthetic words. According to our hypothesis, reading handwriting differs from reading computer text, in part by requiring greater reliance on word-level knowledge (Barnhart & Goldinger, 2010). However, these results may reflect only the inversion of component letters, rather than differences in configural processing. Do configural processes have any explanatory value, beyond differences in letter rotation? In Experiment 1, we addressed this question by standardizing the average angles of tilt across all printed and handwritten exemplars. Using image-editing software, we adjusted the tilt for left- and right-tilting handwritten words, such that their deviations from absolute vertical were equal (although in opposite directions), and we added an identical tilt to typewritten exemplars. The “letter inversion” hypothesis predicts that, under these conditions, equivalent Orientation × Tilt interactions should arise for printed and cursive items. Alternatively, if handwritten words require greater configural processing, the Orientation × Tilt interaction should be larger for cursive words, relative to printed words. Therefore, support for the configural-processing hypothesis would require a three-way Orientation × Tilt × Script interaction.

Method

Participants

A group of 37 Arizona State University undergraduates participated for course credit. All were native English speakers with normal or corrected vision.

Stimuli

We generated 180 five-letter words for the experiment; all were selected from Coney (2005), with equal numbers of low- and high-frequency words (see the Appendix). The mean frequency counts per million (Brysbaert & New, 2009) for the low- and high-frequency words were 3.9 and 87.5, respectively, F(1, 179) = 22.9, p < .0001. Each word was produced in both computer-printed and cursive forms as in Fig. 1. The printed words appeared in 24-pt Courier New font. The handwritten words were collected from two volunteers using a Logitech io2 digital pen; this looks and feels like a standard ballpoint pen, but contains a small camera that reads a fine dot pattern printed on special paper, converting pen strokes into a digital trace. The volunteers were given multiple opportunities to rewrite all of the items until they appeared legible and natural. The trace files were converted to images and were enlarged (comparable to 24-pt font) and sharpened using GIMP2 software.

Once the words were prepared, ten words were randomly sampled, per script; these were used to estimate the average angles of letter tilt for the left- and right-tilting handwriting. The measure tool in GIMP2 was used to determine the angular deviation from vertical of each sampled exemplar. When available, angles were calculated using the longest ascender or descender within the word. The average angle for the left-tilting stimuli was 43 ° from vertical, and the average angle for the right-tilting stimuli was 40 °. We chose the mean, 41.5 °, as our standardized tilt angle for all stimuli in Experiment 1. For the printed stimuli, the “shearing” feature in Adobe Illustrator CS5 was used to adjust the letter tilt 41.5 ° from vertical, in both leftward and rightward directions. The images were then sharpened using the unsharp mask filter in GIMP2. Finally, 12 lists were generated, counterbalancing script, tilt direction, and orientation.

Apparatus

The stimuli were presented using E-Prime 1.2 software on a CRT monitor with a screen resolution of 1,024 × 768. Responses were collected via keyboard.

Procedure

Participants were instructed that they would briefly see words in printed and cursive forms, in different orientations. They were to identify each word, typing it as quickly and accurately as possible. They were asked to refrain from tilting their heads, and were monitored by the experimenter. Each trial began with a 750-ms fixation cross, shown at the spatial beginning of the upcoming word. Thus, the cross was located above center for words rotated clockwise, below center for words rotated counterclockwise, and left of center for words shown horizontally. The cross was replaced by the stimulus word for 500 ms, and participants typed their responses, and were encouraged to guess if necessary. Each trial was followed by accuracy feedback. Following nine practice trials, the experiment included 180 randomized trials.

Results

One participant was excluded from analysis due to excessive errors. We conducted a repeated measures analysis of variance (ANOVA) on error rates (see Fig. 2) with script (print, cursive), tilt (left, right), and orientation (0 °, –90 °, +90 °) as within-subjects variables. To ensure the normality of the data, error rates were arcsine-square-root transformed prior to analysis (Cohen, Cohen, West, & Aiken, 2003).Footnote 1 We observed a large main effect of script, F S(1, 35) = 1,494.5, p < .001, η p 2 = .97, with more errors for cursive words.Footnote 2 Rotation in either direction produced substantial errors, relative to upright words, creating an orientation effect, F S(2, 34) = 159.1, p < .001, η p 2 = .90.Footnote 3 A tilt effect, F S(1, 35) = 49.1, p < .001, η p 2 = .58, reflected greater errors for words with the atypical, leftward tilt.

Fig. 2
figure 2

Experiment 1: Error rates (± SEMs) as a function of script, tilt, and frequency for words at different orientations. LF and HF denote low- and high-frequency words; LT and RT denote left- and right-tilting text, respectively

Full size image

All main effects were qualified by interactions. A Script × Tilt interaction, F S(1, 35) = 51.7, p < .001, η p 2 = .60, reflected a larger tilt effect for cursive words (15.8 %) than for printed words (7.9 %), F S(1, 35) = 18.3, p < .001, η p 2 = .26. An Orientation × Script interaction, F S(2, 34) = 101.1, p < .001, η p 2 = .86 was observed: The average rotation effect was 6.5 % for the printed words, but was 42.1 % for the cursive words, F S(1, 35) = 132.9, p < .001, η p 2 = .79. An Orientation × Tilt interaction, F S(2, 34) = 93.4, p < .001, η p 2 = .85, was observed: Error rates were 17.5 % higher following tilt-consistent rotation, relative to tilt-inconsistent rotation, F S(1, 35) = 25.0, p < .001, η p 2 = .44. Finally, the critical three-way interaction was reliable, F S(2, 34) = 19.4, p < .001, η p 2 = .54. The Orientation × Tilt interaction was larger for cursive words, F S(2, 34) = 84.9, p < .001, η p 2 = .83, than for printed words, F S(2, 34) = 4.48, p < .05, η p 2 = .09.

Because the experimental materials were divided into low- and high-frequency words, we assessed whether the foregoing results differed according to frequency. We found a main effect of frequency, F I(1, 178) = 10.9, p < .01, η p 2 = .06, with 5.1 % more errors to low-frequency words, relative to high-frequency words. Among the five possible interactions, only Script × Frequency was reliable, F I(1, 178) = 36.4, p < .001, η p 2 = .34; the frequency effect was 18.8 % larger when words were written in print, relative to cursive. We will consider this further in the General Discussion.

Discussion

Experiment 1 verified that rotation disproportionately affects handwritten word perception. Printed words elicited few errors across orientations, despite a small effect of orientation. In contrast, cursive words in standard orientation were recognized quite well (80.2 % correct), but rotation in either direction reduced perception, with tilt-consistent rotation producing especially dramatic effects. As noted, we hypothesized that this asymmetry reflects the handwriting tilt. It has been suggested that, during mental rotation (Shepard & Cooper, 1982), people “internally sample” all intermediate positions between an abstract, standard position and the actual position. From this perspective, when a word is rotated clockwise, it becomes a rectangular perceptual object with a “global orientation” of +90 °. Each letter, however, is tilted farther, requiring mental rotation beyond the salient global orientation. If the observer mentally “corrects” the word by rotating it –90 °, he or she will not reach the actual orientations of the letters. Conversely, when the same word is mentally rotated clockwise from a –90 ° orientation, the “correct” orientation of the letters will be achieved prior to reaching 0 °, allowing an opportunity to appreciate the letters and their transitions.

Moving beyond our pilot studies, Experiment 1 involved equivalent tilts across all items, including the typewritten words. We did observe rotation effects with typewritten words, although the effect was substantially larger for handwritten words. This finding suggests that, if rotation disrupts configural processes (Lewis, 2001), such processes are especially important for handwritten words. Handwritten words may be less amenable to a component-processing strategy (which rotation necessitates) by virtue of their connectedness and context-conditioned variation (Barnhart & Goldinger, 2010). Thus, perception of rotated cursive often fails, especially in cases of tilt-consistent rotation.

Experiment 2

Experiment 1 produced the anticipated three-way interaction: Tilt-consistent rotation had stronger effects for handwritten word perception, relative to typewritten word perception. One potential concern, however, is that performance was too accurate to the printed words, such that potential rotation effects were obscured by ceiling effects. Experiment 2 was conducted to replicate Experiment 1, but with visual noise added (to all items). Although there was some risk that degrading the handwritten words could elicit floor effects, such an outcome would “work against” the hypothesized pattern, as it would allow the printed words more “room” to produce a Rotation × Tilt interaction and would reduce that interaction for the handwritten words.

Method

Participants

A group of 47 undergraduates participated for course credit. They were native English speakers with normal or corrected vision.

Stimuli and procedure

The stimuli and procedure were identical to those of Experiment 1, with one exception. For all items, we used Adobe Photoshop to change 80 % of the pixels (in a uniform rectangle around each word) to randomly-selected levels of gray-scale, giving the appearance of words in visual static.

Results

Because the principal goal of Experiment 2 was to reduce performance, particularly for the printed words, we first compared the error rates (see Fig. 3) across Experiments 1 and 2. In a repeated measures ANOVA, we found a main effect of experiment, F S(1, 81) = 21.6, p < .001, η p 2 = .22, with more errors occurring in Experiment 2. We conducted another ANOVA on the printed words alone, finding a similar main effect, F S(1, 35) = 11.5, p < .001, η p 2 = .12. The mean error rates to printed words in Experiments 1 and 2 were 7.9 % and 13.4 %, respectively. Most importantly, when the printed words were rotated, performance moved away from ceiling, with accuracy ranging from 74 % to 90 %.

Fig. 3
figure 3

Experiment 2: Error rates (± SEMs) as a function of script and tilt for degraded words at different orientations. LF and HF denote low- and high-frequency words; LT and RT denote left- and right-tilting text, respectively

Full size image

In other regards, the results of Experiment 2 were similar to those of Experiment 1, as verified by a repeated measures ANOVA on arcsine-transformed error rates with script (print, cursive), tilt (left, right), and orientation (0 °, –90 °, +90 °) as within-subjects variables. We observed a large main effect of script, F S(1, 46) = 1,717.9, p < .001, η p 2 = .98, with more errors for cursive words. A tilt effect, F S(1, 46) = 142.4, p < .001, η p 2 = .76, again reflected higher errors for words with the atypical, leftward tilt. Rotation in either direction produced high error rates, relative to horizontal words, producing an orientation effect, F S(2, 45) = 153.3, p < .001, η p 2 = .87.

As in Experiment 1, all main effects were qualified by interactions, in the same directions. Script interacted with tilt, F S(1, 46) = 83.7, p < .001, η p 2 = .65, with a larger tilt effect for cursive (18 %) than for printed (1 %) words, F S(1, 46) = 49.2, p < .001, η p 2 = .68. An Orientation × Script interaction, F S(2, 45) = 40.3, p < .001, η p 2 = .64, reflected an average rotation effect of 8.3 % for printed words, but an effect of 27.6 % for cursive words, F S(1, 46) = 39.5, p < .001, η p 2 = .51. The Orientation × Tilt interaction, F S(2, 45) = 55.4, p < .001, η p 2 = .71, reflected error rates being 15.2 % higher following tilt-consistent rotation, relative to tilt-inconsistent rotation. Finally, the critical three-way interaction was again reliable, F S(2, 45) = 8.3, p < .01, η p 2 = .22, as the Orientation × Tilt interaction was larger for cursive words, F S(2, 45) = 64.5, p < .001, η p 2 = .74, than for printed words, F S(2, 45) = 6.1, p < .01, η p 2 = .13.

We again assessed whether the results varied according to word frequency. We found a main effect of frequency, F I(1, 178) = 16.7, p < .001, η p 2 = .09, with 7.7 % more errors occurring for low-frequency words. As in Experiment 1, among the possible interactions, only Script × Frequency was reliable, F I(1, 178) = 40.9, p < .001, η p 2 = .38; the frequency effect was 23.1 % larger when words were written in print, relative to cursive.

Discussion

Experiment 2 replicated Experiment 1, with less concern about ceiling effects for printed words: Rotation again interacted with tilt, with maximal errors when the directions of word rotation were consistent with inherent tilt. Although the same general pattern was observed for synthetic and handwritten text, the effect was substantially larger for handwriting. As we will consider in the General Discussion, the difference between reading these forms was not only a matter of scale; there is a qualitative phenomenological difference between reading rotated print and rotated handwriting.

General discussion

In contrast to previous studies, the present results suggest that configural processes can affect word perception, but their role is typically minimized by the use of synthetic print. In handwritten words, many “coarticulatory” cues degrade the letter-level information, naturally shifting perceptual priority to the overall, word-level gestalt. When configural processes were impaired by rotation, the effects were dramatic. In Experiment 1, rotating synthetic words had small (but reliable) effects on printed word recognition, with tilt-consistent rotation increasing errors approximately 5 % more than tilt-inconsistent rotation. With handwritten words, tilt-consistent rotation increased perceptual errors by approximately 30 %, relative to tilt-inconsistent rotation. Experiment 2 replicated this pattern, while added visual noise alleviated concerns regarding ceiling effects for the printed words.

In both experiments, the perceptual effects of rotation did not interact with word frequency, although frequency did affect overall accuracy. We suggest that the present effects are largely prelexical (although further evidence would be required to make a strong claim). This suggestion is partly motivated by the phenomenological experience of attempting to read rotated, handwritten words. Stated simply, while performing this task, on numerous trials the stimulus appears and disappears, and the observer experiences no perceptual coherence at all. (Perhaps this experience was simulated, in reduced form, for readers viewing the sample items in Fig. 1.) In such cases, it is difficult even to guess a couple of letters; making a sophisticated, frequency-biased guess is simply impossible. By contrast, with the computer-printed words, this qualitative experience almost never happens: People nearly always perceive at least a subset of the letters, and can make a guess. Indeed, in both experiments, frequency effects were quite large for printed words and were absent for handwritten words, which underscores the qualitative difference between the conditions.

As noted earlier, we suggest that the “rotated script” effect is conceptually similar to the Thatcher illusion, using words instead of faces: When handwritten words are rotated, their configural integrity is compromised, reducing appreciation for individual letters and their transitions. Although we doubt that similar neural specializations connect these effects (Carbon, Grüter, Weber, & Lueschow, 2007), they appear to be psychologically similar, as part–whole relations are disrupted by disorientation. Indeed, we have recently created a modified version of the Thatcher illusion, modeled after the present experiments with words (Barnhart & Goldinger, The Cockeyed Thatcher Illusion: The relationship of global and local feature orientations affects holistic face processing, in preparation). Specifically, we altered facial photographs, such that each person’s eyes and mouth were rotated 27 °, either clockwise or counterclockwise. When viewed upright, both versions appear equally grotesque. Upon rotating the images, a perceptual effect emerges, analogous to the rotated-script effect: When the faces are turned in the same direction as their tilted features, they appear more normal.

Certainly, the perceptual experiences differ widely between our modified Thatcher illusion and the rotated-script effect. One is expressed as a failure to feel revulsion, the other as a failure of lexical access. Nevertheless, they have underlying similarity: When faces are rotated in the same direction as their internal features, people fail to fully appreciate that “something is wrong.” When handwritten words are rotated in the same direction as their internal features, people often fail to appreciate anything at all. In both phenomena, the importance of configural processing to perception is emphasized by its selective disruption. The present results suggest that word perception can be affected by holistic, word-level processes, but those effects are strongest when the letter-level information becomes noisy. Handwriting provides a natural vehicle for investigating such perceptual compensation processes.