Here, we examined whether our expectations about the weight of an upcoming lift are sufficient to induce the SWI in a single wooden cube when lifted without visual feedback, by varying the size of the object seen prior to the lift during a brief preview.

We also measured fingertip forces during lifts of this cube, in order to determine whether the expectations of heaviness associated with the previewed object would affect the application of grip and load forces We contrasted perceptual and kinetic data with those from a full vision SWI task.

Our previous study showed that forces on early trials were scaled to each participant’s expectations of how much a particular block should weigh ‐ excessive force was applied to the metal block and insufficient force was applied to the polystyrene block. Forces on later trials scaled to the real weight of each block ‐ identical levels of force were applied to all the blocks. MWI persisted throughout – the polystyrene block felt the heaviest and the metal block felt the lightest.We followed this finding up with two experiments:

Experiment 1 – different weight, different material: We adjusted the weight of each block slightly in the opposite direction to the illusion, predicting that we would find opposing perceptual and motor responses (e.g., Grandy & Westwood, 2006).

Experiment 2 – different weight, same material: We also removed the visual differences between the blocks, keeping the slight difference in weight, predicting that the dissociation between perception and action would disappear.

(1) Forces on early trials will scale to each participant’s expectations of how much a particular block will weigh ‐ excessive force will be applied to the metal block and insufficient force applied to the polystyrene block.

(2) Forces on later trials will scale to the real weight of each block ‐ identical levels of force applied to all the blocks.

(3) MWI will persist throughout ‐ polystyrene block will feel the heaviest, metal block will feel the lightest.

• Because we lift in this predictive way, large and small cubes elicit these characteristic errors even when they are adjusted to have equal mass. Lifters will apply too much force to a large cube and substantially less force to a small cube – errors that are rapidly corrected with repeated lifts (Flanagan & Beltzner, 2000).

• When watching others lift objects, an observer’s motor system automatically reacts in a way that reflects the object’s weight (Alaerts et al., 2010). It is, however, unclear how the motor system reacts to observing lifting errors.

• To examine how observing an action improves motor learning in the context of fingertip force scaling, participants watched a video of an object lifting task before lifting equally-weighted large and small cubes themselves.

• To determine what style of kinematic information is more valuable to observe, participants watched either error filled, first-time lifts or error free, expert lifts before lifting these equally-weighted small and large cubes themselves.

The independence of our weight perception and fingertip force application has only been quantified in the right hand of right-handers. The immunity to this perceptual illusion may be affected by manual asymmetries (e.g., Gonzalez, Ganel & Goodale, 2006).

We examined perception of heaviness and fingertip force scaling in right- and left-handers during repeated lifts of SWI-inducing cubes with their dominant and non-dominant hands.

We also examined the optimal direction for intermanual transfer of the scaled fingertip forces. 

• To determine whether characterizing the quality of attachment as a continuous measure impacts the extent to which siblings’ attachment relationships are judged concordant.
• To investigate whether continuous measures of attachment provide additional information regarding the similarity of more specific aspects of siblings attachment relationships.

Model A:

• Mothers’ appraisal of infant temperament was hypothesized to mediate the influence of mothers’ early adversity and depression on maternal sensitivity
• There would be no direct influence of maternal depression

Model B:

• Mothers’ depression was hypothesized to have a direct influence on maternal sensitivity
• Mothers’ perception of infant temperament would not mediate the influence of maternal depression on maternal sensitivity

The current study further explored the origins of attachment relationships for adolescent mothers and their infants by directly comparing the development of these processes with adult mothers and their infants

The hypothesis that differences in the distributions of attachment classifications among these two populations is a result of low levels of sensitivity has yet to be tested in a mediational analysis

The current study will test a model whereby differences in the quality of attachment relationships between these two groups is, at least in part, meditated by maternal sensitivity

However, recent research has identified associations between low levels of maternal sensitivity and Disorganized attachment in high-risk populations (Bernier & Meins, 2008; Moran, Forbes, Evans, Tarabulsy, & Madigan, 2008; van IJzendoorn, Scheungel & Bakermans-Kranenburg, 1999); This raises the possibility that maternal sensitivity may contribute to the development of Disorganized attachment relationships in high-risk groups.

Such findings have yet to be replicated in low-risk samples, perhaps suggesting the association between maternal interactive behaviour and the development of Disorganized attachment may differ between high-risk and low-risk populations.

To better understand differences in the origins of Disorganized relationships between high-risk and low- risk groups, it has been suggested that assessing various aspects of maternal interaction, in addition to overall sensitivity, may be beneficial (Moran et al., 2008).

RESULTS: Maternal sensitivity and perceptions of siblings’ attachment behavior were highly correlated across children of non-Autonomous mothers, but not Autonomous mothers. Non- Autonomous mothers behaved similarly on eight domains of interactive behaviour, while Autonomous mothers behaved similarly on only two.

CONCLUSION: These findings suggest that maternal state of mind is implicated in the ability to flexibly adapt interactive style and relationship-specific attachment perceptions across siblings.

Empirical findings have generally supported this assertion; however, the strength of this association remains a matter of debate as the results of empirical findings have been highly variable (Atkinson et al., 2000; DeWolff & van IJzendoorn, 1997).

Several researchers have suggested that assessing maternal behaviour as a single global dimension may fail to capture important variation in the quality of interactions that influence the developing attachment relationship (van IJzendoorn, 1995; Pederson et al., 1998).

Consequently, assessing distinct aspects of maternal interactive behaviour may provide additional insight into the maternal contribution to the quality of the attachment relationship.