Does performance on the standard antisaccade task meet the co-familiality criterion for an endophenotype?

The “co-familiality” criterion for an endophenotype has two requirements: (1) clinically unaffected relatives as a group should show both a shift in mean performance and an increase in variance compared with controls; (2) performance scores should be heritable. Performance on the antisaccade task is one of several candidate endophenotypes for schizophrenia. In this paper we examine whether the various measures of performance on the standard version of the antisaccade task meet the co-familiality criterion for an endophenotype. The three measures of performance—reflexive saccade errors, latency of correct antisaccades, and gain—show a wide range of effect sizes and variance ratios as well as evidence of significant or near significant heterogeneity. The estimated mean effect sizes [Cohen’s d: error rate: 0.34 (SD: 0.29); latency: 0.33 (SD: 0.30); gain: 0.54 (SD: 0.38)] are significantly greater than 0, but the magnitude of the departures from 0 is relatively small, corresponding to modest effect sizes. The width of the 95% confidence intervals for the estimated effect sizes (error rate: 0.2–0.49; latency: 0.17–0.50; gain: 0.23–0.85) and the coefficients of variation in effect sizes (error rate: 85.3%; latency: 90.9%; gain: 68.4%) reflect heterogeneity in effect sizes. The effect sizes for error rate showed statistically significant heterogeneity and those for latency (P = .07) and gain (P = .09) showed a trend toward heterogeneity. These results indicate that the effect sizes are not consistent with a single mean and that the average effect size may be a biased estimate of the magnitude of differences in performance between relatives of schizophrenics and controls. Relatives of schizophrenics show a small but significant increase in variance in error rate, but the confidence interval is broad, perhaps reflecting the heterogeneity in effect size. The variance ratios for latency and gain did not differ in relatives of schizophrenics and controls. Performance, as measured by error rate, is moderately heritable. The data do not provide compelling support for a consistent shift in mean or variance in relatives of schizophrenia patients compared with nonpsychiatric controls, both of which are required for a major gene involved in co-familial transmission. This set of findings suggests that although intra-familial resemblance in antisaccade performance is due in part to genetic factors, it may not be related to a schizophrenia genotype. Based on the current literature, it would be premature to conclude that any of the measures of antisaccade performance unambiguously meets the co-familiality criterion for an endophenotype.     

Sensitivity to Phonological Similarity Within and Across Languages

The influence of phonological similarity on bilingual language processing was examined within and across languages in three experiments. Phonological similarity was manipulated within a language by varying neighborhood density, and across languages by varying extent of cross-linguistic overlap between native and non-native languages. In Experiment 1, speed and accuracy of bilinguals’ picture naming were susceptible to phonological neighborhood density in both the first and the second language. In Experiment 2, eye-movement patterns indicated that the time-course of language activation varied across phonological neighborhood densities and across native/non-native language status. In Experiment 3, speed and accuracy of bilingual performance in an auditory lexical decision task were influenced by degree of cross-linguistic phonological overlap. Together, the three experiments confirm that bilinguals are sensitive to phonological similarity within and across languages and suggest that this sensitivity is asymmetrical across native and non-native languages and varies along the timecourse of word processing.     

Color change as a causal agent revisited

Michotte (1946/1963, p. 235) concluded that color "has no bearing whatever on the question of qualitative causality". Surprisingly, this claim has received little empirical investigation in the 60 years since its publication. In 2 experiments, 2 balls struck a cylinder and changed color (either continuously or in a stepped progression) for 2 s. After the 2-s interval, the cylinder disgorged a purple substance. Participants chose which of the 2 balls was most likely to have caused the disgorging effect. An object that changed color was favored as the cause much more often than one that did not, and participants generally preferred an object that reached its terminal color immediately before the effect over objects that reached their terminal colors earlier. When participants performed a causal ratings task, color change produced moderate judgments of causation, with little response differentiation as a function of color dynamics.     

The impact of object animacy on the appraisal of causality

The goal of this study was to examine whether animacy of objects affected the appraisal of a causal relationship when one object was observed to propel the other either immediately, after a delay, or at a distance. Participants rated the degree of causal interaction either before or after an extended experience with observing the interactions. We expected that spatial distance would have little effect when objects were seen as animate (because social interactions often span spatial gaps) and would have a degrading effect when objects were appraised as inanimate. Motion animacy appeared to attenuate the impact of a gap and to decrease initial causal judgments for direct collisions. Explicitly informing participants about the nature of the objects had a strong impact. Experience with the causal task affected ratings to a greater extent when the objects were explicitly described as nonliving rather than living.     

Prior experience affects amodal completion in pigeons

In a three-alternative forced-choice task, 4 pigeons were trained to discriminate a target stimulus consisting of two colored shapes, one of which partially occluded the other, from two foil stimuli that portrayed either a complete or an incomplete version of the occluded shape. The dependent measure was the percentage of total errors that the birds committed to the complete foil. At the outset of training, the pigeons committed approximately 50% of total errors to the complete foil, but as training progressed, the percentage of errors to the complete foil rose. When the pigeons were given a second exposure to the initial set of stimuli, they committed 70% of total errors to the complete foil, suggesting that they now saw the complete foil as more similar to the occluded target than the incomplete foil. These results suggest that experience with 2-D images may facilitate amodal completion in pigeons, perhaps via perceptual learning.     

Predictive tracking over occlusions by 4-month-old infants

Two experiments investigated how 16-20-week-old infants visually tracked an object that oscillated on a horizontal trajectory with a centrally placed occluder. To determine the principles underlying infants' tendency to shift gaze to the exiting side before the object arrives, occluder width, oscillation frequency, and motion amplitude were manipulated resulting in occlusion durations between 0.20 and 1.66 s. Through these manipulations, we were able to distinguish between several possible modes of behavior underlying 'predictive' actions at occluders. Four such modes were tested. First, if passage-of-time determines when saccades are made, the tendency to shift gaze over the occluder is expected to be a function of time since disappearance. Second, if visual salience of the exiting occluder edge determines when saccades are made, occluder width would determine the pre-reappearance gaze shifts but not oscillation frequency, amplitude, or velocity. Third, if memory of the duration of the previous occlusion determines when the subjects shift gaze over the occluder, it is expected that the gaze will shift after the same latency at the next occlusion irrespective of whether occlusion duration is changed or not. Finally, if infants base their pre-reappearance gaze shifts on their ability to represent object motion (cognitive mode), it is expected that the latency of the gaze shifts over the occluder is scaled to occlusion duration. Eye and head movements as well as object motion were measured at 240 Hz. In 49% of the passages, the infants shifted gaze to the opposite side of the occluder before the object arrived there. The tendency to make such gaze shifts could not be explained by the passage of time since disappearance. Neither could it be fully explained in terms of visual information present during occlusion, i.e. occluder width. On the contrary, it was found that the latency of the pre-reappearance gaze shifts was determined by the time of object reappearance and that it was a function of all three factors manipulated. The results suggest that object velocity is represented during occlusion and that infants track the object behind the occluder in their 'mind's eye'.     

Practice and Coaching on IQ Tests: Quite a Lot of g

In the present research two studies are used to investigate the relation between g loading of tests and practice (test‐retest) and coaching (active teaching) effects. The data on practice do not support the hypothesis that the higher a test’s g loading, the less susceptible it is to preparation, but the data on coaching support the hypothesis. There is evidence that practice and coaching reduce the g‐loadedness of a collection of tests. The implications of these results for predictive validity, practical usability of the tests, the relevance of traditional intelligence taxonomies, and for future research are discussed.     

Stroop-like interference in chess players' imagery: An unexplored possibility to be revealed by the adapted moving-spot task

Summary A group of highly skilled chess players and two control groups of subjects (nonskilled players and nonplayers) participated in a moving-spot task (cf. Attneave & Curlee, 1983). They had to move either a spot or one of several chess pieces within an imaginary grid according to instructions given by the experimenter (the imaginary motion of the imaginary object consisted of a quasirandom sequence of steps in the direction — up, right, left, or down). The general findings were as follows: (1) chess players' error rates were lower than those in the nonplayer group; (2) in a moving-spot condition there were no significant differences in the efficiency of skilled vs. nonskilled player groups; (3) in a moving chess-piece condition, ranges of spatial errors differed for chess-player and nonplayer groups, depending on the symbolic meaning of the chess pieces in the former group; (4) in a moving chess-piece condition we also found tendencies for Stroop-like interference in the group of skilled players (e. g., bishop moving illegally up, right, etc.); (5) all groups benefitted from the use of a checkerboard instead of an 8 × 8 grid as the imaginary spatial framework within which to move a piece; (6) thepost hoc analysis showed that the two small selected subgroups of subjects comprising those who used either pure visual strategy or pure chess-annotation strategy were susceptible to some Stroop-like interference and that the set of pieces with the highest incongruity of moves (bishop, knight) yielded higher error rates than the set of pieces that had congruity of moves (king, rook). Taken together, these results seem to indicate that visuospatial tasks like Attneave and Curlee's (1983) moving-spot task are performed neither on the basis of a static picture-in-the-head type of visual image, for which it is just the same whether one or another type of piece is imaginarily moved, nor on the basis of purely symbolic or propositional operations that bear no relation to the visual-configurational and spatial-localizational representations. Imagery seems to constitute a dynamicprocess of interplay between visuospatial and verbal-propositional codes.