Governments with their backs against the wall
Ideally, stabilisation using monetary and fiscal policy, alongside actions by the private sector, should restrain the decline in consumption, and yield conditions which are not too harsh for households. At the time of the Great Depression, much less was known of economics. Pegging the currency to gold meant giving up monetary policy autonomy; the US Fed succumbed to contractionary monetary policy once you take into account the closure of banks; the fiscal policy response at the time was miniscule.
It has been argued that the the Smoot-Hawley Tariff Act came about in the US in June 1930, at a point in time where the politicians were coming under enormous pressure to do something. After seven months of inaction by macro policy, with mounting difficulties in the economy, the politicians succumbed to protectionism. This appears to have been of decisive importance in sending the world down the destructive path of competitive trade barriers and cometitive devaluation. In the graph made famous by Barry Eichengreen and Kevin H. O'Rourke, at month 7 there was almost no decline in world trade. Douglas A. Irwin is worth reading on this.
Protectionism adversely impacts the recovery
Greg Mankiw and Scott Sumner point out one more channel through which Smoot-Hawley damaged prospects for the recovery was through the impact of protectionism on confidence.
The private sector saw protectionism as symbolising government backing away from responsible thinking in economics, and responded with a weakening of investment demand. This served to exacerbate the downturn.
Will this time be different?
The bulk of world GDP is now endowed with inflation targeting central banks. This ensures that monetary policy will be counter-cyclical: under bad business cycle conditions, inflation forecasts will drop below targets, and central banks will use every trick in their book to push inflation back up to target.
Fiscal policy has responded well this time around, thanks to better understanding of business cycles when compared with 1929. But there is little headroom to go further.
The world has as little ability to rein in some players engaging in competitive devaluation (e.g. China) today, as was the case in 1930. But with the bulk of world GDP being placed with inflation targeting central banks, the extent to which such tactics will be used will be relatively limited.
So far, we have had an upsurge of protectionism, but nothing on the scale of that seen from 1930 onwards. This could partly reflect the dramatic actions which governments have undertaken through monetary and fiscal policy, through which politicians have been able to reduce the domestic political difficulties that go along with business cycle downturns. But if, in coming months, the world economy remains mired in recession, then we could get fresh pressure to do something. In a recent voxEU post, Jeffrey Frieden points out that the path of adjustment of macroeconomic imbalances and currency distortions will involve political pain along the way, which could spillover into protectionism.
Some protectionist decisions could reflect bargaining tactics aimed at getting China to reduce or end their market manipulation of the currency market. But if there is an upsurge of protectionism beyond this, it will further damage the recovery by hurting investment, giving a spiral of bad economy -> protectionism -> reduced investment demand -> worse economy.