The effects of graded occlusion on manual search and visual attention in 5- to 8-month-old infants

Young infants may be limited in searching for hidden objects because they lack the means-end motor skill to lift occluders from objects. This account was investigated by presenting 5- to 8-month-old infants with objects hidden behind transparent, semitransparent, and opaque curtains. If a means-end deficit explains search limitations, then infants should search no more for an object behind a transparent curtain than for objects behind semitransparent or opaque curtains. However, level of occlusion had a significant effect on manual search and visual attention. Infants retrieved and contacted the object more, contacted the curtain more, and looked away less with the transparent curtain than with the semitransparent or opaque curtains. Adding a time delay before allowing search and presenting a distraction after occlusion further depressed infants' behavior. The findings fail to support the means-end deficit hypothesis, but are consistent with the account that young infants lack object permanence

Object permanence in five-and-a-half-month-old infants?

Event Set x Event Set designs were used to study the rotating screen paradigm introduced by Baillargeon, Spelke, and Wasserman (1985). In Experiment 1, 36 5 1/2 month-old infants were habituated to a screen rotating up to 180 degrees up to and seemingly through a block. All infants were then tested on the same 3 events and also a screen rotating 120 degrees with no block. The results indicate that infants are using novelty and familiarity preference to determine their looking times. To confirm this, in Experiment 2, 52 5 1/2-month-old infants were familiarized on either 3 or 7 trials to a screen rotating 180 degrees with no block or a screen rotating 120 degrees with no block. All infants were then tested on the same test events as Experiment 1. Infants with fewer familiarization trials were more likely to prefer the familiar rotation event. The results of these 2 experiments indicate that infants did not use the possibility or impossibility of events but instead used familiarity or novelty relations between the habituation events and the test events to determine their looking times, and suggest that the Baillargeon et al study should not be interpreted as indicating object permanence or solidity knowledge in young infants

On the interpretation of removable interactions: A survey of the field 33 years after Loftus

In a classic 1978 Memory &Cognition article, Geoff Loftus explained why noncrossover interactions are removable. These removable interactions are tied to the scale of measurement for the dependent variable and therefore do not allow unambiguous conclusions about latent psychological processes. In the present article, we present concrete examples of how this insight helps prevent experimental psychologists from drawing incorrect conclusions about the effects of forgetting and aging. In addition, we extend the Loftus classification scheme for interactions to include those on the cusp between removable and nonremovable. Finally, we use various methods (i.e., a study of citation histories, a questionnaire for psychology students and faculty members, an analysis of statistical textbooks, and a review of articles published in the 2008 issue of Psychology andAging) to show that experimental psychologists have remained generally unaware of the concept of removable interactions. We conclude that there is more to interactions in a 2 × 2 design than meets the eye