The participants here were 23 undergraduate students (16 female) at the University of Calgary who received bonus credit in exchange for participation.
All participants were tested individually. The testing session began with the LDT. In this task, word and nonword stimuli were presented one at a time on a computer screen, and participants were asked to judge whether each stimulus was a real word, making their responses as quickly and accurately as possible. Responses were recorded using a button box with a built in high-accuracy timer. The LDT stimuli were 50 concrete words, 50 abstract words, and 100 nonwords used by Binder, Westbury, McKiernan, Possing and Medler (2005) in a previous study demonstrating a robust concreteness effect in the LDT. The two word groups were matched for length, number of phonemes, mean positional bigram frequency, number of orthographic neighbors, and print frequency (all ps > .49). All participants were presented with half of the stimuli in horizontal orientation and half of the stimuli in vertical orientation. Orientation was counterbalanced such that, across participants, each item was presented equal numbers of times in both orientations. Trials were presented in a different random order to each participant.
We then administered to each participant the following tests: (1) Perceptual speed was assessed with the WAIS III Digit–symbol coding task (Wechsler, 1997), in which participants are presented with nine digit–symbol pairs, and then a list of digits for which they are asked to provide the appropriate symbol, completing as many as possible in 120 s. (2) Category and letter/word fluency were assessed with the Controlled Oral Word Association Test (COWAT; Spreen & Strauss, 1998), in which participants are asked to verbally generate as many animal names as they can (in 60 s) and, separately, to generate words beginning with “F,” “A,” “S,” and, in the present case, “UN” (again, in 60 s apiece), following Tuffiash et al. (2007). (3) Exposure to print was assessed with the Revised Author Recognition Test (Acheson, Wells & MacDonald, 2008), in which participants are presented with a list of 130 names and are asked to identify which are the names of real authors (65 are real author names). (4) Vocabulary was assessed with the short form of the North American Adult Reading Test (NAART35; Uttl, 2002), in which participants are asked to pronounce 35 English words of irregular spelling as accurately as possible. And, finally, (5) anagramming skill was assessed by asking participants to solve 51 computer-presented anagrams (Tuffiash et al., 2007). The order of these assessments was counterbalanced across participants. Mean scores for these measures are presented in Table 1.
For each participant, LDT response latencies greater than 3 SDs from that participant’s cell mean for each condition were excluded from the analyses (1.6% of the data). Response errors comprised 6.4% of trials. The mean response latencies of correct responses and mean error percentages for all stimulus types are presented in Table 2. In all cases, analyses were conducted with subjects (F
1) and, separately, items (F
2) treated as random factors.
LDT response latencies for word trials were analyzed with 2 (orientation: horizontal, vertical) × 2 (concreteness: concrete, abstract) ANOVAs. Significant results included main effects of orientation [F
1(1, 22) = 57. 14, p < .001, η
2 = .78; F
2(1, 98) = 107.89, p < .001, η
2 = .52] and concreteness [F
1(1, 22) = 55.11, p < .001, η
2 = .72; F
2(1, 98) = 7.26, p = .008, η
2 = .07], such that responses were faster for words in horizontal orientation and for concrete words. The interaction of orientation and concreteness was not significant [F
1(1, 22) = 2.95, p = .10, η
2 = .10; F
2(1, 98) = 1.00, p = .323, η
2 = .01].
Similarly, LDT response errors for word trials were analyzed with 2 (orientation: horizontal, vertical) × 2 (concreteness: concrete, abstract) ANOVAs. The main effect of concreteness was significant by subjects and approached significance by items [F
1(1, 22) = 14.64, p = .001, η
2 = .40; F
2(1, 98) = 3.01, p = .081, η
2 = .04], such that responses were more accurate for concrete than for abstract words. The main effect of orientation and the interaction of orientation and concreteness were not significant (both Fs < 1).
LDT response latencies for nonword trials were analyzed with one-way (orientation: horizontal, vertical) ANOVAs. The results included a main effect of orientation [F
1(1, 22) = 112.36, p < .001, η
2 = .84; F
2(1, 99) = 215.43, p < .001, η
2 = .69] because responses were faster for nonwords in the horizontal orientation.
Similarly, LDT response errors for nonword trials were analyzed with one-way (orientation: horizontal, vertical) ANOVAs. The results included a main effect of orientation [F
1(1, 22) = 6.18, p = .021, η
2 = .22; F
2(1, 99) = 3.84, p = .053, η
2 = .04] because responses were more accurate for nonwords in the horizontal orientation.
The results of Experiment 1 showed a robust concreteness effect in LDT for words presented in both horizontal and vertical orientations (in both the latency and error data), as well as faster responses for words and nonwords presented horizontally. Thus, the task and stimuli seemed to generate the expected behavioral effects with a typical undergraduate sample. We next examined how performance in this task was modulated by specific word recognition experience.