Differences between left- and right-handers in approach/avoidance motivation: influence of consistency of handedness measures

Hand preference is often viewed as a troublesome variable in psychological research, with left-handers routinely excluded from studies. Contrary to this, a body of evidence has shown hand preference to be a useful variable when examining human behavior. A recent review argues that the most effective way of using handedness as a variable, is a comparison between individuals who use their dominant hand for virtually all manual activities (consistent handers) versus those who use their other hand for at least one activity (inconsistent handers). The authors contend that researchers should only focus on degree of handedness rather than direction of preference (left versus right). However, we argue that the field suffers from a number of methodological and empirical issues. These include a lack of consensus in choice of cut-off point to divide consistent and inconsistent categories and importantly a paucity of data from left-handers. Consequentially, researchers predominantly compare inconsistent versus consistent right-handers, largely linked to memory, cognition and language. Other research on response style and personality measures shows robust direction of handedness effects. The present study examines both strength and direction of handedness on self-reported behavioral inhibition system (BIS) and behavioral activation system (BAS) scores, using evidence from a large (N = 689) dataset including more than 200 left-handers. There were degree of handedness effects on BIS and BAS-Fun Seeking, but effects are largely driven by differences between consistent left-handers and other groups. Choice of cut-off point substantively influenced results, and suggests that unless a suitable sample of left-handers is included, researchers clarify that their degree of handedness effects are applicable only to right-handers. We concur that strength of hand preference is an important variable but caution that differences related to consistency may not be identical in right and left-handers

Are left-handers really more anxious?

Research examining anxiety and handedness is inconclusive. Davidson and Schaffer (1983) found left-handers had higher trait anxiety, while Beaton and Moseley (1991) found no state or trait differences. Such studies potentially have methodological issues, and we have argued that handedness related reactivity differences (Wright & Hardie, 2011) suggest that state anxiety needs to be measured within a context. Thus the current study investigated state and trait anxiety levels in an experimental situation. We found left-handers had significantly higher state scores, supporting the right hemisphere's role in negative affect and inhibition. It also fits with predictions based on the behavioural inhibition system's role in the revised reinforcement sensitivity theory (rRST). No trait differences were found, but there was a significant relationship between trait and state anxiety. Using ANCOVA to control for the influence of trait anxiety on state anxiety, we still found a handedness effect. When participant's trait anxiety levels were similar, left-handers showed a relatively larger state response. We conclude that in the context of an experiment, state anxiety was directly correlated with trait anxiety but that the relatively higher reactivity of left-handers may be a major influence on how they respond in a new situation

The relationship between Revised Reinforcement Sensitivity Theory (rRST), handedness and indecision

Indecisiveness is an inability to make a decision, manifest across a number of behaviours. We explore the influence that both direction and strength of hand preference may have on this construct, examining it in relation to the revised Reinforcement Sensitivity Theory (rRST). Frost and Shows’ (1993) Indecisiveness Scale was administered to 328 undergraduates (221 females), alongside the Edinburgh Handedness Inventory (Oldfield, 1971) and Carver and White’s (1994) BIS/BAS scales. Simple correlations showed left-handers had a positive relationship between strength of handedness and BIS. In right-handers, strength and aversive indecision were positively correlated. Regression analysis demonstrated no significant relationship between hand strength and indecision, but that indecision was related to all three measures of rRST. Consistent with previous work, BIS was positively related to all indecision but particularly aversive, while BAS was negatively related to indecision but most strongly the avoidant category. We found that FFFS is more closely related to aversive than avoidant indecision. The relationship between rRST and indecision may be influenced by handedness; for right-handers the same pattern was found, but in left-handers BAS was not a significant predictor of indecision, BIS only predicted aversive indecision and FFFS predicted all three categories

Influences of lateral preference and personality on behaviour towards a manual sorting task

Differences in task behaviour between left- and right-handers and left- and right-eared individuals have been reported (e.g. Jackson, 2008 and Wright et al., 2004) with left-handers taking longer to begin a task and right-eared individuals having a more disinhibited approach. Personality measurements are also important when examining approach behaviour. Jackson (2008) reported that those with higher neuroticism levels and a right-ear preference react faster to tasks. The current study investigated the effects of lateral preference and personality on behaviour towards a manual sorting task. Eighty-five participants completed laterality and personality scales and a card-sorting task. Degree of hand preference was found to influence behaviour towards the task with strong left-handers taking longer to begin. Those with a left congruent lateral preference (left-hand, left-ear) took significantly longer to begin the task than those with a right congruent preference. Neither neuroticism nor extraversion influenced task approach. We concluded that hand preference, and more specifically a strong left-hand preference is a good predictor of a longer initiation time on a manual task. Ear preference on its own does not predict initiation time

Handedness and behavioural inhibition:left-handed females show most inhibition as measured by BIS/BAS self-report

This study investigated the relationship between handedness, gender and behavioural approach and inhibition using Carver and White’s (1994) BIS/BAS Scale. 112 participants took part: 46 left-handers and 66 right-handers. All participants completed Peters’ (1998) handedness questionnaire followed by the self-report BIS/BAS Scale. Significant effects of both handedness and gender on the BIS scores were found, with left-handers and females scoring significantly higher on inhibition. BIS scores were re-examined to include FFFS scores, which showed a significant effect of gender. Revised BIS scores replicated the original BIS findings. These findings are discussed in relation to handedness research

Handedness and social anxiety:using Bryden's research as a catalyst to explore the influence of familial sinistrality and degree of handedness

Phil Bryden's work has impacted on many areas of laterality, including degree and measurement of hand preference, as well as influences of familial sinistrality (FS). For example, Bryden[(1977). Measuring handedness with questionnaires. Neuropsychologia, 15, 617–624] is a well-cited and influential paper that remains relevant to this day. Inspired by this we extended our analysis of the relationship between handedness and anxiety in a number of ways. We used familial handedness and strength of handedness to examine their potential influences on anxiety, and extended our research by exploring their relationship to social anxiety, using the Social Phobia Inventory (SPIN). Inconsistent left-handers (ILH) were found to be more socially anxious. In all categories of SPIN except avoidance, ILH were significantly more anxious than consistent right- and left-handers. There were FS differences between ILH with a first degree left-handed relative (FS+) compared to ILH with no first degree left-handed relative (FS−) on all categories of anxiety scores. Within FS+ participants, ILH had significantly higher anxiety scores, compared with consistent handers across all categories. This suggests that ILH's social anxiety may be influenced by a close left-handed relative. Inspired by examining Bryden's work for this special issue, we will continue to add both strength of preference and familial handedness to our work

King size onions not wanted on the local market

WESTERN AUSTRALIA produced 3,500 tons of onions in 1955 and 7,000 tons in 1964. This 100 per cent, increase was achieved with only a 39 per cent, increase in acreage, so that crops produced much higher yields

Onion seed production at the Vegetable Research Station

THE production of a uniform line of good onions is a problem to many onion growers in Western Australia. This is caused largely by the difficulty in producing or obtaining satisfactory pure high quality seed in this State

Sunflowers as a cover crop for market gardens.

The quantity of organic manure available to vegetable growers seems to decrease each year and it has therefore been necessary to seek other means of maintaining both soil fertility and the supply of humus which are essential for growing quality vegetables. This is doubly necessary in Western Australia since most of the vegetables are grown in close proximity to the metropolitan area where the soil is of a sandy nature and relatively infertile

Scene-based nonuniformity correction with video sequences and registration

We describe a new, to our knowledge, scene-based nonuniformity correction algorithm for array detectors. The algorithm relies on the ability to register a sequence of observed frames in the presence of the fixed-pattern noise caused by pixel-to-pixel nonuniformity. In low-to-moderate levels of nonuniformity, sufficiently accurate registration may be possible with standard scene-based registration techniques. If the registration is accurate, and motion exists between the frames, then groups of independent detectors can be identified that observe the same irradiance (or true scene value). These detector outputs are averaged to generate estimates of the true scene values. With these scene estimates, and the corresponding observed values through a given detector, a curve-fitting procedure is used to estimate the individual detector response parameters. These can then be used to correct for detector nonuniformity. The strength of the algorithm lies in its simplicity and low computational complexity. Experimental results, to illustrate the performance of the algorithm, include the use of visible-range imagery with simulated nonuniformity and infrared imagery with real nonuniformity